As filed with the Securities and Exchange Commission on May 6, 1998
                                                      Registration No. 333-

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                       AMERICAN TOWER SYSTEMS CORPORATION
             (Exact name of registrant as specified in its charter)

               Delaware                               65-0598206
        (State or other jurisdiction of           (I.R.S. Employer
         incorporation or organization)          Identification No.)

               116 Huntington Avenue, Boston, Massachusetts 02116
         (Address, including zip code, of principal executive offices)

           American Tower Systems Corporation 1997 Stock Option Plan,
                    as Amended and Restated on April 27, 1998;
                         Exchanged Option Agreements(3)
                            (Full title of the Plan)

                                 STEVEN B. DODGE
                       American Tower Systems Corporation
                              116 Huntington Avenue
                           Boston, Massachusetts 02116
                                 (617) 375-7500
 (Name, address, including zip code, and telephone number, including area code,
                              of agent for service)

                                    Copy to:
                             NORMAN A. BIKALES, ESQ.
                            Sullivan & Worcester LLP
                             One Post Office Square
                           Boston, Massachusetts 02109
                                 (617) 338-2800

CALCULATION OF REGISTRATION FEE Proposed Proposed Amount Maximum Maximum Title of Each Class of to be Offering Price Aggregate Amount of Securities to be Registered Registered Per Share Offering Price Registration Fee - -------------------------------------------------------------------------------------------------------------------- Common Stock, $.01 par value.............. (1) $ (2) (2) $81,460 ==================================================================================================================== (1) Consists of an aggregate of 15,000,000 shares of Class A Common Stock, $.01 par value per share ("Class A Common") and Class B Common Stock, $.01 par value per share ("Class B Common") authorized under the American Tower Systems Corporation 1997 Stock Option Plan, as Amended and Restated on April 27, 1998 and 2,150,000 shares authorized under the Exchanged Option Agreements. (2) Pursuant to Rule 457(h) the offering price is calculated based upon the exercise price with respect to 7,392,640 shares subject to options currently outstanding and, for the remainder of the shares, the average of the bid and ask prices in the "when-issued" trading market on May 4, 1998 in accordance with Rule 457(c) under the Securities Act. (3) Exchanged Option Agreements (the "Exchanged Option Agreements") entered into between the Company and Alan Box, Arnold Chavkin, Steven Dodge, James Eisenstein, Ross Elder, Peter Kovaleski, Thomas Stoner and Joseph Winn entered into pursuant to the consummation of the merger of American Radio Systems Corporation with a subsidiary of CBS Corporation (the "Merger").
AMERICAN TOWER SYSTEMS CORPORATION REGISTRATION STATEMENT ON FORM S-8 PART I INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS Item 1. Plan Information; Item 2. Registrant Information and Employee Plan Annual Information. The documents containing the information required by these items will be given to employees participating in the American Tower Systems Corporation 1997 Stock Option Plan, as Amended and Restated on April 27, 1998 (the "Plan") and are not required to be filed with the Securities and Exchange Commission (the "Commission") as part of the Registration Statement or as an exhibit thereto. PART II INFORMATION REQUIRED IN THE REGISTRATION STATEMENT Item 3. Incorporation of Documents by Reference. The following documents which have been filed by the Company with the Commission are incorporated by reference in and made a part of this Registration Statement, as of their respective dates: (a) The Company's Annual Report on Form 10-K for the fiscal year ended December 31, 1997; and (b) The Company's Form 8-Ks filed on May 1, 1998 and March 20, 1998. All documents subsequently filed by the Company pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act prior to the filing of a post-effective amendment which indicates that all securities offered have been sold or which deregisters all securities then remaining unsold, shall be deemed to be incorporated by reference in this Registration Statement and to be part hereof from the date of filing of such documents. Any statement contained in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this Registration Statement to the extent that a statement herein, or in any subsequently filed document which also is or is deemed to be incorporated by reference, modifies or supersedes such statement. Any statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this Registration Statement. Item 4. Description of Securities. The description of the Common Stock contained under the caption "Description of American Tower Systems Capital Stock" in the Company's Prospectus dated February 17, 1998 and filed with the Commission pursuant to Rule 424(b) are hereby incorporated by reference (File No. 333-46025). Item 5. Interests of Named Experts and Counsel. The validity of the shares offered hereby will be passed upon for the Company by Sullivan & Worcester LLP, Boston, Massachusetts. Norman A. Bikales, a member of the firm of Sullivan & Worcester LLP, upon consummation of the Merger, will be the owner of 9,000 shares of Class A Common and 41,490 shares of Class B Common and II-1 currently has an option to purchase 20,000 shares of Class A Common Stock at $10.00 per share. Mr. Bikales and/or associates of that firm serve as secretary or assistant secretaries of the Company and certain of its subsidiaries. Item 6. Indemnification of Directors and Officers. Section 145 of the Delaware General Corporation Law (the "DGCL") provides, in effect, that any person made a party to any action by reason of the fact that he is or was a director, officer, employee or agent of the Company may and, in certain cases, must be indemnified by the Company against, in the case of a non-derivative action, judgments, fines, amounts paid in settlement and reasonable expenses (including attorney's fees), if in either type of action he acted in good faith and in a manner he reasonably believed to be in or not opposed to the best interests of the Company and, in a non-derivative action, which involves a criminal proceeding, in which such person had no reasonable cause to believe his conduct was unlawful. This indemnification does not apply, in a derivative action, to matters as to which it is adjudged that the director, officer, employee or agent is liable to the Company, unless upon court order it is determined that, despite such adjudication of liability, but in view of all the circumstances of the case, he is fairly and reasonably entitled to indemnity for expenses. Article XII of the Company's By-Laws provides that the Company shall indemnify each person who is or was an officer or director of the Company to the fullest extent permitted by Section 145 of the DGCL. Article Sixth of the Company's Restated Certificate of Incorporation states that no director of the Company shall be personally liable to the Company or its stockholders for monetary damages for breach of fiduciary duty as a director, except for (i) breach of the director's duty of loyalty to the Company or its stockholders, (ii) acts or omissions not in good faith or which involve intentional misconduct or knowing violation of law, (iii) liability under Section 174 of the DGCL relating to certain unlawful dividends and stock repurchases, or (iv) any transaction from which the director derived an improper personal benefit. Item 7. Exemption from Registration Claimed. Not applicable. Item 8. Exhibits. Listed below are the exhibit which are filed as part of this registration statement (according to the number assigned to them in Item 601 of Regulation S-K).
Exhibit No. Description of Document Exhibit File No. 5 Opinion of Sullivan & Worcester LLP.............................Filed herewith as Exhibit 5 10.1 American Tower Systems Corporation 1997 Stock Option Plan, dated as of November 5, 1997, as Amended and Restated on April 27, 1998..................................................Filed herewith as Exhibit 10.1 23.0 Consent of Sullivan & Worcester LLP.............................Contained in the opinion of Sullivan & Worcester LLP filed herewith as part of Exhibit 5 23.1 Consent of Deloitte & Touche LLP................................Filed herewith as Exhibit 23.1 24 Power of Attorney...............................................Filed herewith as page II-4 of the Registration Statement
Item 9. Undertakings. (a) The undersigned registrant hereby undertakes: (1) to file, during any period in which offers or sales are being made, a post-effective amendment to this Registration Statement: II-2 (i) to include any prospectus required by Section 10(a)(3) of the Securities Act of 1933; (ii) to reflect in the prospectus any facts or events arising after the effective date of the Registration Statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement; (iii) to include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement: provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in periodic reports filed by the Company pursuant to Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement; (2) that, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof; and (3) to remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering; (b) For purposes of determining any liability under the Securities Act of 1933, each filing of the Company's annual report pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan's annual report pursuant to Section 15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the Registration Statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof; and (c) Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the Company pursuant to the foregoing provisions, or otherwise, the Company has been advised that in the opinion of the Commission such indemnification is against public policy as expressed in that Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the Company of expenses incurred or paid by a director, officer or controlling person of the Company in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the Company will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act of 1933 and will be governed by the final adjudication of such issue. II-3 SIGNATURES Pursuant to the requirements of the Securities Act of 1933, the Company certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Boston, Commonwealth of Massachusetts, on the 28th day of April, 1998. AMERICAN TOWER SYSTEMS CORPORATION By: /s/ Steven B. Dodge Steven B. Dodge Chairman of the Board, President and Chief Executive Officer The undersigned Officers and Directors of American Tower Systems Corporation (the "Company") hereby severally constitute Joseph L. Winn, Justin D. Benincasa, Michael B. Milsom and Norman A. Bikales, and each of them, acting singly, our true and lawful attorneys to sign for us and in our names in the capacities indicated below the Company's Registration Statement on Form S-8 relating to the registration of an aggregate of 17,150,000 shares of the Company's Class A Common Stock, $.01 par value, and Class B Common Stock, $.01 par value, issued or issuable upon the exercise of options granted under the American Tower Systems Corporation 1997 Stock Option Plan, as Amended and Restated on April 27, 1998, and the Exchanged Option Agreements, and any and all amendments and supplements thereto, filed with the Securities and Exchange Commission, for the purpose of registering such shares, under the Securities Act of 1933, as amended, granting unto each of said attorneys, acting singly, full power and authority to do and perform each and every act and thing requisite or necessary to be done in and about the premises, as fully to all intents and purposes as he might or could do in person, hereby ratifying and confirming our signatures to said registration statement signed by our said attorneys and all else that said attorneys may lawfully do and cause to be done by virtue hereof. Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed below by the following persons on behalf of the Company and in the capacities and on the dates indicated. Signature Title Date /s/ Steven B. Dodge Chairman, President and April 28, 1998 Steven B. Dodge Chief Executive Officer /s/ Joseph L. Winn Chief Financial Officer and April 28, 1998 Joseph L. Winn Director /s/ Justin D. Benincasa Vice President and April 28, 1998 Justin D. Benincasa Corporate Controller /s/ Alan L. Box Executive Vice President and April 28, 1998 Alan L. Box Director /s/ Arnold L. Chavkin Director April 28, 1998 Arnold L. Chavkin /s/ J. Michael Gearon, Jr. Executive Vice President and April 28, 1998 J. Michael Gearon, Jr. Director II-4 Signature Title Date /s/ Thomas H. Stoner Director April 28, 1998 Thomas H. Stoner II-5 EXHIBIT INDEX Listed below are the exhibit which are filed as part of this registration statement (according to the number assigned to them in Item 601 of Regulation S-K).
Exhibit No. Description of Document Exhibit File No. Page 5 Opinion of Sullivan & Worcester LLP.............................Filed herewith as Exhibit 5 10.1 American Tower Systems Corporation 1997 Stock Option Plan, dated as of November 5, 1997, as Amended and Restated on April 27, 1998..................................................Filed herewith as Exhibit 10.1 23.0 Consent of Sullivan & Worcester LLP.............................Contained in the opinion of Sullivan & Worcester LLP filed herewith as part of Exhibit 5 23.1 Consent of Deloitte & Touche LLP................................Filed herewith as Exhibit 23.1 24 Power of Attorney...............................................Filed herewith as page II-4 of the Registration Statement
II-6
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                       AMERICAN TOWER SYSTEMS CORPORATION

                             1997 Stock Option Plan
                    As Amended and Restated on April 27, 1998



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AMERICAN TOWER SYSTEMS CORPORATION 1997 STOCK OPTION PLAN TABLE OF CONTENTS Page 1. PURPOSE.........................................................................................1 2. ADMINISTRATION OF THE PLAN......................................................................1 3. OPTION SHARES...................................................................................2 4. AUTHORITY TO GRANT OPTIONS......................................................................2 5. WRITTEN AGREEMENT...............................................................................2 6. ELIGIBILITY.....................................................................................3 7. OPTION PRICE....................................................................................3 8. DURATION OF OPTIONS.............................................................................4 9. VESTING PROVISIONS..............................................................................4 10. EXERCISE OF OPTIONS.............................................................................4 11. TRANSFERABILITY OF OPTIONS......................................................................5 12. TERMINATION OF EMPLOYMENT OR INVOLVEMENT OF OPTIONEE WITH THE COMPANY................................................................................6 13. REQUIREMENTS OF LAW.............................................................................6 14. NO RIGHTS AS STOCKHOLDER........................................................................7 15. EMPLOYMENT OBLIGATION...........................................................................7 16. FORFEITURE AS A RESULT OF TERMINATION FOR CAUSE ................................................7 17. CHANGES IN THE COMPANY'S CAPITAL STRUCTURE......................................................8 18. AMENDMENT OR TERMINATION OF PLAN................................................................9 19. EFFECTIVE DATE AND DURATION OF THE PLAN........................................................10
AMERICAN TOWER SYSTEMS CORPORATION 1997 STOCK OPTION PLAN 1. PURPOSE The purpose of this 1997 Stock Option Plan (the "Plan") is to encourage directors, consultants and employees of American Tower Systems Corporation (the "Company") and its Subsidiaries (as hereinafter defined) to continue their association with the Company and its Subsidiaries, by providing opportunities for such persons to participate in the ownership of the Company and in its future growth through the granting of stock options (the "Options") which may be options designed to qualify as incentive stock options (within the meaning of Section 422 of the Internal Revenue Code of 1986, as amended (the "Code") (an "ISO"), or options not intended to qualify for any special tax treatment under the Code (a "NQO"). The term "Subsidiary" as used in the Plan means a corporation or other business organization of which the Company owns, directly or indirectly through an unbroken chain of ownership, fifty percent (50%) or more of the total combined voting power of all classes of stock. 2. ADMINISTRATION OF THE PLAN The Plan shall be administered by a committee (the "Committee") consisting of two or more members of the Company's Board of Directors (the "Board"). The Committee shall from time to time determine to whom options or other rights shall be granted under the Plan, whether options granted shall be incentive stock options ("ISOs") or nonqualified stock options ("NSOs"), the terms of the options or other rights, and the number of shares that may be granted under options. The Committee shall report to the Board the names of individuals to whom stock or options or other rights are to be granted, the number of shares covered, and the terms and conditions of each grant. The determinations described in this Section 2 may be made by the Committee or by the Board, as the Board shall direct in its discretion, and references in the Plan to the Committee shall be understood to refer to the Board in any such case. The Committee shall select one of its members as Chairman and shall hold meetings at such times and places as it may determine. A majority of the Committee shall constitute a quorum, and acts of the Committee at which a quorum is present, or acts reduced to or approved in writing by all the members of the Committee, shall be the valid acts of the Committee. The Committee shall have the authority to adopt, amend, and rescind such rules and regulations as, in its opinion, may be advisable in the administration of the Plan. All questions of interpretation and application of such rules and regulations, of the Plan and of options granted thereunder (the "Options"), shall be subject to the determination of the Committee, which shall be final and binding. The Plan shall be administered in such a manner as to permit those Options granted hereunder and specially designated under Section 5 hereof as an ISO to qualify as incentive stock options as described in Section 422 of the Internal Revenue Code of 1986, as amended (the "Code"). For so long as Section 16 of the Securities Exchange Act of 1934, as amended from time to time (the "Exchange Act"), is applicable to the Company, each member of the Committee shall be a "non-employee director" or the equivalent within the meaning of Rule 16b-3 under the Exchange Act, and, for so long as Section 162(m) of the Code is applicable to the Company, an "outside director" within the meaning of Section 162 of the Code and the regulations thereunder. With respect to persons subject to Section 16 of the Exchange Act ("Insiders"), transactions under the Plan are intended to comply with all applicable conditions of Rule 16b-3 or its successor under the Exchange Act. To the extent any provision of the Plan or action by the Committee fails to so comply, it shall be deemed to be modified so as to be in compliance with such Rule, or, if such modification is not possible, it shall be deemed to be null and void, to the extent permitted by law and deemed advisable by the Committee. 3. OPTION SHARES The stock subject to Options under the Plan shall be shares of Class A and Class B Common Stock, par value $.01 per share (the "Stock"), provided, however, that after the consummation of the ATC Merger as defined in the Agreement and Plan of Merger by and between the Company and American Tower Corporation, dated December 12, 1997, as may be amended, any Options granted shall be for shares of Class A. The total amount of the Stock with respect to which Options may be granted (the "Option Pool"), shall not exceed in the aggregate 15,000,000 shares; provided, however, such aggregate number of shares shall be subject to adjustment in accordance with the provisions of Section 17. In the event that any outstanding Option shall expire for any reason or shall terminate by reason of the death or severance of employment of the Optionee, the surrender of any such Option, or any other cause, the shares of Stock allocable to the unexercised portion of such Option may again be subject to an option under the Plan. The maximum number of shares of Stock subject to Options that may be granted to any Optionee in the aggregate in any calendar year shall not exceed 5,000,000 shares. 4. AUTHORITY TO GRANT OPTIONS The Committee may determine, from time to time, which employees of the Company or any Subsidiary or other persons shall be granted Options under the Plan, the terms of the Options (including without limitation whether an Option shall be an ISO or a NQO) and the number of shares which may be purchased under the Option or Options. Without limiting the generality of the foregoing, the Committee may from time to time grant: (a) to such employees (other than employees of a Subsidiary which is not a corporation) as it shall determine an Option or Options to buy a stated number of shares of Stock under the terms and conditions of the Plan which Option or Options will to the extent so designated at the time of grant constitute an ISO; and (b) to such eligible directors, employees or other persons as it shall determine an Option or Options to buy a stated number of shares of Stock under the terms and conditions of the Plan which Option or Options shall constitute a NQO. Subject only to any applicable limitations set forth elsewhere in the Plan, the number of shares of Stock to be covered by any Option shall be as determined by the Committee. 5. WRITTEN AGREEMENT Each Option granted hereunder shall be embodied in an option agreement (the "Option Agreement") substantially in the form of Exhibit 1, which shall be signed by the Optionee and by -2- the Chief Executive Officer, Chief Financial Officer or the Corporate Controller of the Company for and in the name and on behalf of the Company. An Option Agreement may contain such restrictions on exercisability and such other provisions not inconsistent with the Plan as the Committee in its sole and absolute discretion shall approve. 6. ELIGIBILITY The individuals who shall be eligible for grant of Options under the Plan shall be employees (including officers who may be members of the Board), directors who are not employees and other individuals, whether or not employees, who render services of special importance to the management, operation, or development of the Company or a Subsidiary, and who have contributed or may be expected to contribute materially to the success of the Company or a Subsidiary. An employee, director or other person to whom an Option has been granted pursuant to an Option Agreement is hereinafter referred to as an "Optionee." 7. OPTION PRICE The price at which shares of Stock may be purchased pursuant to an Option shall be specified by the Committee at the time the Option is granted, but shall in no event be less than the par value of such shares and, in the case of an ISO, except as set forth in the following sentence, one hundred percent (100%) of the fair market value of the Stock on the date the ISO is granted. In the case of an employee who owns (or is considered under Section 424(d) of the Code as owning) stock possessing more than ten percent (10%) of the total combined voting power of all classes of stock of the Company or any Subsidiary, the price which shares of Stock may be so purchased pursuant to an ISO shall be not less than one hundred and ten percent (110%) of the fair value of the Stock on the date the ISO is granted. For purposes of the Plan, the "fair market value" of a share of Stock on any date specified herein, shall mean (a) the last reported sales price, regular way, or, in the event that no sale takes place on such day, the average of the reported closing bid and asked prices, regular way, in either case (i) as reported on the New York Stock Exchange Composite Tape, or (ii) if the Stock is not listed or admitted to trading on the New York Stock Exchange, on the principal national securities exchange on which such security is listed or admitted to trading, or (iii) if not then listed or admitted to trading on any national securities exchange, on the NASDAQ National Market System; or (b) if the Stock is not quoted on such National Market System, (i) the average of the closing bid and asked prices on each such day in the over-the-counter market as reported by NASDAQ, or (ii) if bid and asked prices for such security on each such day shall not have been reported through NASDAQ, the average of the bid and asked prices for such day as furnished by any New York Stock Exchange member firm regularly making a market in such security selected for such purpose by the Committee; or (c) if the Stock is not then listed or admitted to trading on any national exchange or quoted in the over-the-counter market, the fair value thereof determined in good faith by the Committee as of a date which is within thirty (30) days of the date with respect to which the determination is to be made; provided, however, that any method of determining fair market value employed by the Committee with respect to an ISO shall be consistent with any applicable laws or regulations pertaining to "incentive stock options." -3- 8. DURATION OF OPTIONS The duration of any Option shall be specified by the Committee in the Option Agreement, but no ISO shall be exercisable after the expiration of ten (10) years, and no NQO shall be exercisable after the expiration of ten (10) years and one (1) day, from the date such Option is granted. In the case of any employee who owns (or is considered under Section 424(d) of the Code as owning) stock possessing more than ten percent (10%) of the total combined voting power of all classes of stock of the Company or any Subsidiary, no ISO shall be exercisable after the expiration of five (5) years from the date such Option is granted. The Committee, in its sole and absolute discretion, may extend any Option theretofore granted subject to the aforesaid limits and may provide that an Option shall be exercisable during its entire duration or during any lesser period of time. 9. VESTING PROVISIONS Each Option may be exercised so long as it is valid and outstanding from time to time, in part or as a whole, in such manner and subject to such conditions as the Committee, in its sole and absolute discretion, may provide in the Option Agreement. 10. EXERCISE OF OPTIONS Options shall be exercised by the delivery of written notice to the Company setting forth the number of shares of Stock with respect to which the Option is to be exercised, accompanied by payment of the option price of such shares, which payment shall be made, subject to the alternative provisions of this Section, in cash or by such cash equivalents, payable to the order of the Company in an amount in United States dollars equal to the option price of such shares, as the Committee in its sole and absolute discretion shall consider acceptable. Such notice shall be delivered in person to the Secretary of the Company or shall be sent by registered mail, return receipt requested, to the Secretary of the Company, in which case delivery shall be deemed made on the date such notice is deposited in the mail. Alternatively, if the Option Agreement so specifies, and subject to such rules as may be established by the Committee, payment of the option price may be made through a so-called "cashless exercise" procedure, under which the Optionee shall deliver irrevocable instructions to a broker to sell shares of Stock acquired upon exercise of the Option and to remit promptly to the Company a sufficient portion of the sale proceeds to pay the option price and any tax withholding resulting from such exercise. Alternatively, payment of the option price may be made, in whole or in part, in shares of Stock owned by the Optionee; provided, however, that the Optionee may not make payment in shares of Stock that he acquired upon the earlier exercise of any ISO (or other "incentive stock option"), unless and until he has held the shares until at least two (2) years after the date the ISO (or such other incentive stock option) was granted and at least one (1) year after the date the ISO (or such other option) was exercised. If payment is made in whole or in part in shares of Stock, then the Optionee shall deliver to the Company in payment of the option price of the shares with respect of which such Option is exercised (a) certificates registered in the name of such Optionee representing a number of shares of Stock legally and beneficially owned by such Optionee, free of -4- all liens, claims and encumbrances of every kind, and having a fair market value on the date of delivery of such notice equal to the option price of the shares of Stock with respect to which such Option is to be exercised, such certificates to be accompanied by stock powers duly endorsed in blank by the record holder of the shares of Stock represented by such certificates; and (b) if the option price of the shares with respect to which such Option is to be exercised exceeds such fair market value, cash or such cash equivalents payable to the order to the Company, in an amount in United States dollars equal to the amount of such excess, as the Committee in its sole and absolute discretion shall consider acceptable. Notwithstanding the foregoing provisions of this Section, the Committee, in its sole and absolute discretion (i) may refuse to accept shares of Stock in payment of the option price of the shares of Stock with respect to which such Option is to be exercised and, in that event, any certificates representing shares of Stock which were delivered to the Company with such written notice shall be returned to such Optionee together with notice by the Company to such Optionee of the refusal of the Committee to accept such shares of Stock and (ii) may accept, in lieu of actual delivery of stock certificates, an attestation by the Optionee substantially in the form attached herewith as Exhibit C or such other form as may be deemed acceptable by the Committee that he or she owns of record the shares to be tendered free and clear of all liens, claims and encumbrances of every kind. Alternatively, if the Option Agreement so specifies, payment of the option price may be made in part by a promissory note executed by the Optionee and containing the following terms and conditions (and such others as the Committee shall, in its sole and absolute discretion determine from time to time): (a) it shall be collaterally secured by the shares of Stock obtained upon exercise of the Option; (b) repayment shall be made on demand by the Company and, in any event, no later than three (3) years from the date of exercise; and (c) the note shall bear interest at a rate as determined by the Committee, payable monthly out of a payroll deduction provision; provided, however, that notwithstanding the foregoing (i) an amount not less than the par value of the shares of Stock with respect to which the Option is being exercised must be paid in cash, cash equivalents, or shares of Stock in accordance with this Section, and (ii) the payment of such exercise price by promissory note does not violate any applicable laws or regulations, including, without limitation, Delaware corporate law or applicable margin lending rules. The decision as to whether to permit partial payment by a promissory note for shares of Stock to be issued upon exercise of any Option granted shall rest entirely in the sole and absolute discretion of the Committee. As promptly as practicable after the receipt by the Company of (a) written notice from the Optionee setting forth the number of shares of Stock with respect to which such Option is to be exercised and (b) payment of the option price of such shares in the form required by the foregoing provisions of this Section, the Company shall cause to be delivered to such Optionee certificates representing the number of shares with respect to which such Option has been so exercised (less a number of shares equal to the number of shares as to which ownership was attested under the procedure described in clause (ii) of the next preceding paragraph). 11. TRANSFERABILITY OF OPTIONS Options shall not be transferable by the Optionee otherwise than by will or under the laws of descent and distribution, and shall be exercisable during his or her lifetime only by the Optionee, except that the Committee may specify in an Option Agreement that pertains to an NQO that the Optionee may transfer such NQO to a member of the Immediate Family of the Optionee, to a trust -5- solely for the benefit of the Optionee and the Optionee's Immediate Family, or to a partnership or limited liability company whose only partners or members are the Optionee and members of the Optionee's Immediate Family. "Immediate Family" shall mean, with respect to any Optionee, such Optionee's child, stepchild, grandchild, parent, stepparent, grandparent, spouse, sibling, mother-in-law, father-in-law, son-in-law, daughter-in-law, brother-in-law, or sister-in-law, and shall include adoptive relationships. 12. TERMINATION OF EMPLOYMENT OR INVOLVEMENT OF OPTIONEE WITH THE COMPANY For purposes of this Section, employment by or involvement with (in the case of an Optionee who is not an employee) a Subsidiary shall be considered employment by or involvement with the Company. Except as otherwise set forth in the Option Agreement, after the Optionee's termination of employment with the Company other than by reason of death or disability, including his retirement in good standing from the employ of the Company for reasons of age under the then established rules of the Company, the Option shall terminate on the earlier of the date of its expiration or three (3) months after the date of such termination or retirement. After the death of the Optionee, his or her executors, administrators or any persons to whom his or her Option may be transferred by will or by the laws of descent and distribution shall have the right to exercise the Option to the extent to which the Optionee was entitled to exercise the Option. In the event that such termination is a result of disability, the Optionee shall have the right to exercise the Option pursuant to its terms as if such Optionee continued as an employee. Authorized leave of absence or absence on military or government service shall not constitute severance of the employment relationship between the Company and the Optionee for purposes of the Plan, provided that either (a) such absence is for a period of no more than ninety (90) days or (b) the Employee's right to re-employment after such absence is guaranteed either by statute or by contract. For Optionees who are not employees of the Company, options shall be exercisable for such periods following the termination of the Optionee's involvement with the Company as may be set forth in the Option Agreement. 13. REQUIREMENTS OF LAW The Company shall not be required to sell or issue any shares of Stock upon the exercise of any Option if the issuance of such shares shall constitute or result in a violation by the Optionee or the Company of any provisions of any law, statute or regulation of any governmental authority. Specifically, in connection with the Securities Act of 1933, as amended (the "Securities Act"), and any applicable state securities or "blue sky" law (a "Blue Sky Law"), upon exercise of any Option the Company shall not be required to issue such shares unless the Committee has received evidence satisfactory to it to the effect that the holder of such Option will not transfer such shares except pursuant to a registration statement in effect under the Securities Act and Blue Sky Laws or unless an opinion of counsel satisfactory to the Company has been received by the Company to the effect that such registration and compliance is not required. Any determination in this connection by the Committee shall be final, binding and conclusive. The Company shall not be obligated to take any action in order to cause the exercise of an Option or the issuance of shares of Stock pursuant thereto -6- to comply with any law or regulations of any governmental authority, including, without limitation, the Securities Act or applicable Blue Sky Law. Notwithstanding any other provision of the Plan to the contrary, the Company may refuse to permit transfer of shares of Stock if in the opinion of its legal counsel such transfer would violate federal or state securities laws or subject the Company to liability thereunder. Any sale, assignment, transfer, pledge or other disposition of shares of Stock received upon exercise of any Option (or any other shares or securities derived therefrom) which is not in accordance with the provisions of this Section shall be void and of no effect and shall not be recognized by the Company. Legend on Certificates. The Committee may cause any certificate representing shares of Stock acquired upon exercise of an Option (and any other shares or securities derived therefrom) to bear a legend to the effect that the securities represented by such certificate have not been registered under the Federal Securities Act of 1933, as amended, or any applicable state securities laws, and may not be sold, assigned, transferred, pledged or otherwise disposed of except in accordance with the Plan and applicable agreements binding the holder and the Company or any of its stockholders. 14. NO RIGHTS AS STOCKHOLDER No Optionee shall have any rights as a stockholder with respect to shares covered by his or her Option until the date of issuance of a stock certificate for such shares; except as otherwise provided in Section 17, no adjustment for dividends or otherwise shall be made if the record date therefor is prior to the date of issuance of such certificate. 15. EMPLOYMENT OBLIGATION The granting of any Option shall not impose upon the Company or any Subsidiary any obligation to employ or continue to employ any Optionee, or to engage or retain the services of any person, and the right of the Company or any Subsidiary to terminate the employment or services of any person shall not be diminished or affected by reason of the fact that an Option has been granted to him or her. The existence of any Option shall not be taken into account in determining any damages relating to termination of employment or services for any reason. 16. FORFEITURE AS A RESULT OF TERMINATION FOR CAUSE Notwithstanding any provision of the Plan to the contrary, if the Committee determines, after full consideration of the facts presented on behalf of the Company and an Optionee, that (a) the Optionee has been engaged in fraud, embezzlement, theft, commission of a felony or dishonesty in the course of his or her employment by or involvement with the Company or a Subsidiary, which damaged the Company or a Subsidiary, or has made unauthorized disclosure of trade secrets or other proprietary information of the Company or a Subsidiary or of a third party who has entrusted such information to the Company or a Subsidiary, or -7- (b) the Optionee's employment or involvement was otherwise terminated for "cause," as defined in any employment agreement with the Optionee, if applicable, or if there is no such agreement, as determined by the Committee, which may determine that "cause" includes among other matters the willful failure or refusal of the Optionee to perform and carry out his or her assigned duties and responsibilities diligently and in a manner satisfactory to the Committee, then the Optionee's right to exercise an Option shall terminate as of the date of such act (in the case of (a)) or such termination (in the case of (b)) and the Optionee shall forfeit all unexercised Options. If an Optionee whose behavior the Company asserts falls within the provisions of (a) or (b) above has exercised or attempts to exercise an Option prior to a decision of the Committee, the Company shall not be required to recognize such exercise until the Committee has made its decision and, in the event of any exercise shall have taken place, it shall be of no force and effect (and void ab initio) if the Committee makes an adverse determination; provided, however, if the Committee finds in favor of the Optionee then the Optionee will be deemed to have exercised such Option retroactively as of the date he or she originally gave written notice of his or her attempt to exercise or actual exercise, as the case may be. The decision of the Committee as to the cause of an Optionee's discharge and the damage done to the Company or a Subsidiary shall be final, binding and conclusive. No decision of the Committee, however, shall affect in any manner the finality of the discharge of such Optionee by the Company or a Subsidiary. 17. CHANGES IN THE COMPANY'S CAPITAL STRUCTURE The existence of outstanding Options shall not affect in any way the right or power of the Company or its stockholders to make or authorize any or all adjustments, recapitalizations, reorganizations or other changes in the Company's capital structure or its business or any merger or consolidation of the Company or any issue of bonds, debentures, preferred or preference stock, whether or not convertible into the Stock or other securities, ranking prior to the Stock or affecting the rights thereof, or warrants, rights or options to acquire the same, or the dissolution or liquidation of the Company or any sale or transfer of all or any part of its assets or business or any other corporate act or proceeding, whether of a similar character or otherwise. The number of shares of Stock in the Option Pool (less the number of shares theretofore delivered upon exercise of Options) and the number of shares of Stock covered by any outstanding Option and the price per share payable upon exercise thereof (provided that in no event shall the option price be less than the par value of such shares) shall be proportionately adjusted for any increase or decrease in the number of issued and outstanding shares of Stock resulting from any subdivision, split, combination or consolidation of shares of Stock or the payment of a dividend in shares of stock or other securities of the Company on the Stock. The decision of the Board as to the adjustment, if any, required by the provisions of this Section shall be final, binding and conclusive. If the Company merges or consolidates with a wholly-owned subsidiary for the purpose of reincorporating itself under the laws of another jurisdiction, the Optionees will be entitled to acquire shares of Stock of the reincorporated Company upon the same terms and conditions as were in effect immediately prior to such reincorporation (unless such reincorporation involves a change in the number of shares or the capitalization of the Company, in which case proportional adjustments shall -8- be made as provided above) and the Plan, unless otherwise rescinded by the Board, will remain the Plan of the reincorporated Company. Except as otherwise provided in the preceding paragraph, if the Company is merged or consolidated with another corporation, whether or not the Company is the surviving entity, or if the Company is liquidated or sells or otherwise disposes of all or substantially all of its assets to another entity while unexercised Options remain outstanding under the Plan, or if other circumstances occur in which the Board in its sole and absolute discretion deems it appropriate for the provisions of this paragraph to apply (in each case, an "Applicable Event"), then (a) each holder of an outstanding Option shall be entitled, upon exercise of such Option, to receive in lieu of shares of Stock, such stock or other securities or property as he or she would have received had he exercised such option immediately prior to the Applicable Event; or (b) the Board may, in its sole and absolute discretion, waive, generally or in one or more specific cases, any limitations imposed pursuant to Section 9 so that some or all Options from and after a date prior to the effective date of such Applicable Event, specified by the Board, in its sole and absolute discretion, shall be exercisable in full; or (c) the Board may, in its sole and absolute discretion, cancel all outstanding and unexercised Options as of the effective date of any such Applicable Event; or (d) the Board may, in its sole discretion, convert some or all Options into options to purchase the stock or other securities of the surviving corporation pursuant to an Applicable Event; or (e) the Board may, in its sole and absolute discretion, assume the outstanding and unexercised options to purchase stock or other securities of any corporation and convert such options into Options to purchase Stock, whether pursuant to this Plan or not, pursuant to an Applicable Event; provided, however, notice of any such cancellation pursuant to clause (c) shall be given to each holder of an Option not less than thirty (30) days preceding the effective date of such Applicable Event, and provided further, however, that the Board may, in its sole and absolute discretion, waive, generally or in one or more specific instances, any limitations imposed pursuant to Section 9 with respect to any Option so that such Option shall be exercisable in full or in part, as the Board may, in its sole and absolute discretion, determine, during such thirty (30) day period. Except as expressly provided herein, the issue by the Company of shares of Stock or other securities of any class or series or securities convertible into or exchangeable or exercisable for shares of Stock or other securities of any class or series for cash or property or for labor or services either upon direct sale or upon the exercise of rights or warrants to subscribe therefor, or upon conversion of shares or obligations of the Company convertible into such shares or other securities, shall not affect, and no adjustment by reason thereof shall be made with respect to, the number, class or price of shares of Stock then subject to outstanding Options. 18. AMENDMENT OR TERMINATION OF PLAN The Board may, in its sole and absolute discretion, modify, revise or terminate the Plan at any time and from time to time; provided, however, that without the further approval of the holders of at least a majority of the outstanding shares of Stock, the Board may not (a) materially increase the benefits accruing to Optionees under the Plan or make any "modifications" as that term is defined under Section 424(h)(3) (or its successor) of the Code if such increase in benefits or modifications would adversely affect (i) the availability to the Plan of the protections of Section 16(b) of the Exchange Act, if applicable to the Company, or (ii) the qualification of the Plan or any Options for "incentive stock option" treatment under Section 422 of the Code; (b) change the aggregate number of shares of Stock which may be issued under Options pursuant to the provisions -9- of the Plan either to any one employee or in the aggregate; or (c) change the class of persons eligible to receive ISOs. Notwithstanding the preceding sentence, the Board shall in all events have the power and authority to make such changes in the Plan and in the regulations and administrative provisions hereunder or in any outstanding Option as, in the opinion of counsel for the Company, may be necessary or appropriate from time to time to enable any Option granted pursuant to the Plan to qualify as an incentive stock option or such other stock option as may be defined under the Code, as amended from time to time, so as to receive preferential federal income tax treatment. 19. EFFECTIVE DATE AND DURATION OF THE PLAN The Plan shall become effective and shall be deemed to have been adopted on November 5, 1997, unless the Plan shall have terminated earlier, the Plan shall terminate on the tenth (10th) anniversary of its effective date, and no Option shall be granted pursuant to the Plan after the day preceding the tenth (10th) anniversary of its effective date. -10- AMERICAN TOWER SYSTEMS CORPORATION Stock Option Agreement Option Certificate: No. Specific Terms of the Option Subject to the terms and conditions hereinafter set forth and the terms and conditions of the American Tower Systems Corporation 1997 Stock Option Plan (the "Plan"), American Tower Systems Corporation, a Delaware corporation (the "Company" which term shall include, unless the context otherwise clearly requires, all Subsidiaries [as defined in the Plan] of the Company) hereby grants the following option to purchase shares of Common Stock, par value $.01 per share (the "Stock") of the Company: 1. Name of Person to Whom the Option is granted (the "Optionee"): 2. Date of Grant of Option: 3. Number of shares of Stock: 4. Option Exercise Price (per share): $ 5. Term: Subject to Section 10, this Option expires at 5:00 p.m. Eastern Time on 6. Exercisability: Provided that on the dates set forth below the Optionee is still employed by the Company or, if the Optionee is not employed by the Company the Optionee is still actively involved in the Company (as determined by the Committee) the Option will become exercisable as follows and as provided in Section 9 below: Date Number of Shares Cumulative Number American Tower Systems Corporation By:__________________________ X_______________________ Title:____________________ (Signature of Optionee) Date:_______________ Optionee's Address: OTHER TERMS OF THE OPTION WHEREAS, the Board of Directors (the "Board") has authorized the grant of stock options upon certain terms and conditions set forth in the Plan and herein; and WHEREAS, the Compensation Committee (the "Committee") has authorized the grant of this stock option pursuant and subject to the terms of the Plan, a copy of which is available from the Company and is hereby incorporated herein; NOW, THEREFORE, in consideration of the premises and the mutual covenants and agreements herein contained, the Company and the Optionee, intending to be legally bound, covenant and agree as set forth on the first page hereof and as follows: 7. Grant. Pursuant and subject to the Plan, the Company does hereby grant to the Optionee a stock option (the "Option") to purchase from the Company the number of shares of Stock set forth in Section 3 on the first page hereof upon the terms and conditions set forth in the Plan and upon the additional terms and conditions contained herein. This Option is a [incentive] [nonqualified] stock option and [is] [is not] intended to qualify for special federal income tax treatment as an "incentive stock option" pursuant to Section 422 of the Internal Revenue Code of 1986, as amended (the "Code"). 8. Option Price. This Option may be exercised at the option price per share of Stock set forth in Section 4 on the first page hereof, subject to adjustment as provided herein and in the Plan. 9. Term and Exercisability of Option. This Option shall expire on the date determined pursuant to Section 5 on first page hereof and shall be exercisable prior to that date in accordance with and subject to the conditions set forth in the Plan and those conditions, if any, set forth in Section 6 on first page hereof. If before this Option has been exercised in full, the Optionee ceases to be an employee of the Company for any reason other than a termination for a reason specified in Section 16 of the Plan, the Optionee may exercise this Option to the extent that he or she might have exercised it on the date of termination of his or her employment, but only during the period ending on the earlier of (a) the date on which the Option expires in accordance with Section 5 of this Agreement or (b) three (3) months after the date of termination of the Optionee's employment with the Company. However, if the Optionee dies before the date of expiration of this Option and while in the employ of the Company or during the three month period described in the preceding sentence, or in the event of the retirement of the Optionee for reasons of disability (within the meaning of Code ss. 22(e)(3)), the Option shall terminate only on such date of expiration. If the Optionee dies before this Option has been exercised in full, the personal representative of the Optionee may exercise this Option as set forth in the preceding sentence. 10. Method of Exercise. To the extent that the right to purchase shares of Stock has accrued hereunder, this Option may be exercised from time to time by written notice to the Company substantially in the form attached hereto as Exhibit A, stating the number of shares with respect to which this Option is being exercised, and accompanied by payment in full of the option price for the number of shares to be delivered, by means of payment acceptable to the Company in accordance with Section 10 of the Plan. As soon as practicable after its receipt of such notice, the Company -2- shall, without transfer or issue tax to the Optionee (or other person entitled to exercise this Option), deliver to the Optionee (or other person entitled to exercise this Option), at the principal executive offices of the Company or such other place as shall be mutually acceptable, a certificate or certificates for such shares out of theretofore authorized but unissued shares or reacquired shares of its Stock as the Company may elect; provided, however, that the time of such delivery may be postponed by the Company for such period as may be required for it with reasonable diligence to comply with any applicable requirements of law. Payment of the option price may be made in cash or cash equivalents or, in accordance with the terms and conditions of Section 10 of the Plan, (a) in whole or in part in shares of Common Stock of the Company, whether or not through the attestation procedure in the Plan, or (b) in part by promissory note of the Optionee in the form attached hereto as Exhibit B; provided, however, that the Board reserves the right upon receipt of any written notice of exercise from the Optionee to require payment in cash with respect to the shares contemplated in such notice. If the Optionee (or other person entitled to exercise this Option) fails to pay for and accept delivery of all of the shares specified in such notice upon tender of delivery thereof, his or her right to exercise this Option with respect to such shares not paid for may be terminated by the Company. 11. Nonassignability of Option Rights. This Option shall not be assignable or transferable by the Optionee except by will or by the laws of descent and distribution. During the life of the Optionee, this Option shall be exercisable only by him or her.* 12. Compliance with Securities Act. The Company shall not be obligated to sell or issue any shares of Stock or other securities pursuant to the exercise of this Option unless the shares of Stock or other securities with respect to which this Option is being exercised are at that time effectively registered or exempt from registration under the Securities Act of 1933, as amended, and applicable state securities laws. In the event shares or other securities shall be issued which shall not be so registered, the Optionee hereby represents, warrants and agrees that he or she will receive such shares or other securities for investment and not with a view to their resale or distribution, and will execute an appropriate investment letter satisfactory to the Company and its counsel. 13. Legends. The Optionee hereby acknowledges that the stock certificate or certificates evidencing shares of Stock or other securities issued pursuant to any exercise of this Option will bear a legend setting forth the restrictions on their transferability described in Section 13 hereof. 14. Rights as Stockholder. The Optionee shall have no rights as a stockholder with respect to any shares of Stock or other securities covered by this Option until the date of issuance of a certificate to him or her for such shares or other securities. No adjustment shall be made for dividends or other rights for which the record date is prior to the date such stock certificate is issued. 15. Withholding Taxes. The Optionee hereby agrees, as a condition to any exercise of this Option, to provide to the Company an amount sufficient to satisfy its obligation to withhold certain federal, state and local taxes arising by reason of such exercise (the "Withholding Amount") by (a) authorizing the Company to withhold the Withholding Amount from his or her cash compensation, - -------- * Use different language for an Option transferable to family members. -3- or (b) remitting the Withholding Amount to the Company in cash; provided, however, that to the extent that the Withholding Amount is not provided by one or a combination of such methods, the Company in its sole and absolute discretion may refuse to issue such shares of Stock or may withhold from the shares of Stock delivered upon exercise of this Option that number of shares having a fair market value, on the date of exercise, sufficient to eliminate any deficiency in the Withholding Amount. 16. Notice of Disqualifying Disposition. If this Option is an incentive stock option, the Optionee agrees to notify the Company promptly in the event that he sells, transfers, exchanges or otherwise disposes of any shares of Stock issued upon exercise of the Option, before the later of (i) the second anniversary of the date of grant of the Option and (ii) the first anniversary of the date the shares were issues upon his exercise of the Option. 17. Termination or Amendment of Plan. The Board may in its sole and absolute discretion at ant time terminate or from time to time modify and amend the Plan, but no such termination or amendment will affect rights and obligations under this Option. 18. Effect Upon Employment. Nothing in this Option or the Plan shall be construed to impose any obligation upon the Company to employ or retain in its employ, or continue its involvement with, the Optionee. 19. Time for Acceptance. Unless the Optionee shall evidence his or her acceptance of this Option by execution of this Agreement within seven (7) days after its delivery to him or her, the Option and this Agreement shall be null and void. 20. General Provisions. (a) Amendment; Waivers. This Agreement, including the Plan, contains the full and complete understanding and agreement of the parties hereto as to the subject matter hereof and may not be modified or amended, nor may any provision hereof be waived, except by a further written agreement duly signed by each of the parties. The waiver by either of the parties hereto of any provision hereof in any instance shall not operate as a waiver of any other provision hereof or in any other instance. (b) Binding Effect. This Agreement shall inure to the benefit of and be binding upon the parties hereto and, to the extent provided herein and in the Plan, their respective heirs, executors, administrators, representatives, successors and assigns. (c) Construction. This Agreement is to be construed in accordance with the terms of the Plan. In case of any conflict between the Plan and this Agreement, the Plan shall control. The titles of the sections of this Agreement and of the Plan are included for convenience only and shall not be construed as modifying or affecting their provisions. The masculine gender shall include both sexes; the singular shall include the plural and the plural the singular unless the context otherwise requires. -4- (d) Governing Law. This Agreement shall be governed by and construed and enforced in accordance with the applicable laws of the United States of America and the law (other than the law governing conflict of law questions) of The Commonwealth of Massachusetts except to the extent the laws of any other jurisdiction are mandatorily applicable. (e) Notices. Any notice in connection with this Agreement shall be deemed to have been properly delivered if it is in writing and is delivered in hand or sent by registered mail to the party addressed as follows, unless another address has been substituted by notice so given: To the Optionee: To his or her address as listed on the books of the Company. To the Company: American Tower Systems Corporation 116 Huntington Avenue Boston, MA 02116 Attention: Chief Financial Officer and Sullivan & Worcester LLP One Post Office Square Boston, MA 02109 Attention: Norman A. Bikales -5- Exhibit A to Stock Option [FORM FOR EXERCISE OF STOCK OPTION] American Tower Systems Corporation 116 Huntington Avenue Boston, Massachusetts 02116 RE: Exercise of Option under American Tower Systems Corporation 1997 Stock Option Plan Gentlemen: Please take notice that the undersigned hereby elects to exercise the stock option granted to ___________ (the "Employee") pursuant and subject to the terms and conditions of the Stock Option Agreement between the Employee and the Company dated as of , 199 (the "Option Agreement") by and to the extent of purchasing shares of [Class A or Class B] Common Stock, par value $.01 per share, of American Tower Systems Corporation (the "Company") for the option price of $_____ per share. The undersigned encloses herewith payment, in cash or in such other property as is permitted under the Plan of the purchase price for said shares. If the undersigned is making payment of any part of the purchase price by delivery of shares of Common Stock of the Company, he or she hereby confirms that he or she has investigated and considered the possible income tax consequences to him or her of making such payments in that form. The undersigned hereby agrees to provide the Company an amount sufficient to satisfy the obligation of the Company to withhold certain taxes, as provided in Section 15 of the Option Agreement. The undersigned hereby specifically confirms to American Tower Systems Corporation that he or she is acquiring said shares for investment and not with a view to their sale or distribution, and that said shares shall be held subject to all of the terms and conditions of said Stock Option Agreement. Very truly yours, _____________________ __________________________________ Date (Signed by the Employee or other party duly exercising option) Exhibit B to Stock Option [FORM OF TERM NOTE IN PAYMENT OF EXERCISE PRICE OF OPTIONS] PROMISSORY NOTE $_____________ Date:__________ FOR VALUE RECEIVED, the undersigned (the "Payor") hereby promises to pay to the order of American Tower Systems Corporation (the "Payee") at the principal office of Payee in Boston, Massachusetts ON DEMAND and in any event on or before ___________19__ the sum of _______________________ ($_______________) with interest from the date hereof on the principal amount hereof from time to time unpaid at the rate of ___ percent (___%) per annum. Interest on the outstanding principal amount hereof shall be due and payable monthly on the last business day of each month in each year during the term of this Note, and at maturity commencing with the month end immediately following the date of this Note. The Payor authorizes the Payee to withhold such interest from his regular monthly or other salary payment or other compensation and to apply such withheld amount to interest due hereon and also agrees to execute such instruments and other documents as the Payee may from time to time request to reflect such right of withholding. [The Payor shall on ______ of each year, commencing in ____, pay an amount equal to ____ percent (__%) of the original principal amount of this Note, together with all accrued and unpaid interest thereon.] All payments on this Note shall be first applied against accrued but unpaid interest to the extent thereof, and then to the outstanding principal amount. The Payor shall have the right to prepay the principal amount of this Note in whole or in part at any time without penalty, but together with all but unpaid accrued interest on the outstanding principal amount. No such prepayment shall affect the obligation of the Payor to make the payments required by the last sentence of the first paragraph of this Note. Payor shall pay principal, interest, and other amounts under, and in accordance with the terms of, this Note, free and clear of and without deduction for any and all present and future taxes, levies, imposts, deductions, charges, withholdings, and all liabilities with respect thereto, excluding taxes measured by income. Should the indebtedness evidenced by this Note or any part thereof be collected by legal action, or in bankruptcy, receivership or other court proceedings, or should this Note be placed in the hands of attorneys for collection after default, Payor agrees to pay, upon demand by Holder, in addition to principal and interest and other sums, if any, due and payable hereon, court costs and reasonable attorneys' fees and other reasonable collection charges, to the maximum extent permitted by applicable law. This Note represents the obligation of the Payor to pay on an installment basis the balance of the purchase price of shares of Common Stock of the Payee to be issued to the Payor promptly after the date hereof (the "Shares"), plus interest on such purchase price, pursuant to a stock option granted pursuant to the Stock Option Agreement dated _________, 199_ (the "Agreement"). Upon the occurrence of any of the following events (an "acceleration event"): (a) Failure of the Payor to perform or observe any of his obligations under this Note or the Agreement, or acceleration of the payor's obligation to make payment of the purchase price of the Shares pursuant to the provisions of the Agreement; or (b) Commencement of voluntary or involuntary proceedings in respect of the Payor under any federal or state bankruptcy, insolvency, receivership or other similar law; or (c) Termination of the Payor's employment by the Payee; then, and in any such event, the holder of this Note at its election may forthwith declare the entire principal amount of this Note, together with accrued interest thereon, immediately due and payable, and this Note shall thereupon forthwith become so due and payable without presentation, protest or further demand or notice of any kind, all of which are expressly waived. The Payor hereby waives the presentment, demand, notice of protest and all other demands and notices in connection with delivery, acceptance, performance, default or enforcement hereof. No delay or omission on the part of the holder of this Note in exercising any right hereunder shall operate as a waiver of such right or of any other right hereunder, no course of dealing between the Payor and the holder shall operate as a waiver of any of the holder's rights hereunder unless set forth in a writing signed by the holder, and a waiver on any one occasion shall not be construed as a bar to or waiver of any right on any future occasion. The Payor further agrees to pay the costs, fees and expenses (including reasonable attorneys' fees) of collection and enforcement of this Note. Any provision of this Note to the contrary notwithstanding, changes in or additions to this Note may be made, or compliance with any term, covenant, agreement, condition or provision set forth herein may be omitted or waived (either generally or in a particular instance and either retroactively or prospectively) with, but only with, the consent in writing of Holder and Payor, and each such change, addition or waiver shall be binding upon each future holder of the Note and Payor. Any consent may be given subject to satisfaction of conditions stated therein. This Note shall be binding upon and shall inure to the benefit of the Payor and the Payee and their respective successors and assigns, including, without limitation, successors by operation of law pursuant to any merger, consolidation or sale of assets involving any of the parties. This Note shall be deemed to be a contract made under and to be construed in accordance with and governed by the applicable law of the United States of America and the laws (other than the law governing conflict of law matters) of The Commonwealth of Massachusetts. -2- If the last or appointed day for taking of any action required or permitted hereby (other than the payment of principal of or interest or premium, if any, hereon) shall be a Saturday, Sunday or legal holiday in Boston, Massachusetts, or a day on which banking institutions in Boston, Massachusetts are authorized by law or executive order to close, then such action may be taken on the next succeeding business day for banking institutions in such city. This Note is executed as, and shall be effective as, a sealed instrument and shall be binding upon the estate and any successor of the Payor. Witness:_________________________ ____________________________ Print Name: Print Name: -3- Exhibit C to Stock Option ATTESTATION FORM Pursuant to the Notice of Exercise submitted herewith, I have elected to purchase ________ shares of American Tower Systems Corporation (the "Company") [Class A or Class B] Common Stock at $____ per share, as stated in the Stock Option agreement dated __________. I hereby attest to ownership of the shares under the certificate(s) listed below and hereby tender such shares in full or partial payment of the total Option Price of $___________. I also certify that I either (i) have held the shares I am tendering for at least one year after acquiring such shares through the exercise of an ISO, or (ii) have not obtained such shares through the exercise of an ISO. Although the Company has not required me to make actual delivery of my certificates, as a result of which I (and the joint owner, if any, of the shares listed below) will retain ownership of the shares, I represent that I, with the consent of the joint owner (if any) of the shares, have full power to deliver and convey the certificates to the Company and therefore could have caused the Company to become sole owner of the shares. The joint owner of the shares, by signing this form, consents to the above representations and the exercise of the stock option by this notice.
[Class A or Class B] No. of Shares Acquired by Date of Common Stock Represented Stock Option Acquisition Certificate(s) Plan Exercise (Yes/No) - ------------------------------------ ----------------------- ------------------------- ----------------- - ------------------------------------ ----------------------- ------------------------- ----------------- - ------------------------------------ ----------------------- ------------------------- ----------------- - ------------------------------------ ----------------------- ------------------------- -----------------
You are hereby instructed to apply toward the Option Price: (Check one) The maximum number of whole shares necessary to pay the Option Price, or, if fewer, the total number of shares represented by the listed certificate(s), with any remaining amount to be paid by check accompanying this Attestation Form. _____________________ of the listed shares, with any remaining amount to be paid by check accompanying this Attestation Form. If I have paid only a portion of the total Option Price by tendering Company [Class A or Class B] Common Stock, enclosed herewith is a check payable to Company in the amount of $____________ for the balance of the Option Price. -4-
                                                                       EXHIBIT 5
                              SULLIVAN & WORCESTER LLP
                               ONE POST OFFICE SQUARE
                             BOSTON, MASSACHUSETTS 02109
                                   (617) 338-2800
                                FAX NO. 617-338-2880
     IN WASHINGTON, D.C.                                   IN NEW YORK CITY
1025 CONNECTICUT AVENUE, N.W.                              767 THIRD AVENUE
   WASHINGTON, D.C. 20036                              NEW YORK, NEW YORK 10017
       (202) 775-8190                                       (212) 486-8200
    FAX NO. 202-293-2275                                 FAX NO. 212-758-2151






                                                     May 5, 1998



American Radio Systems Corporation
116 Huntington Avenue
Boston, MA 02116

     Re:  Registration  Statement  on Form  S-8 of an  Aggregate  of  17,150,000
          Shares of Class A Common Stock and Class B Common Stock

Dear Sir or Madam:

         In connection with the  registration  under the Securities Act of 1933,
as amended (the  "Securities  Act"),  by American Tower Systems  Corporation,  a
Delaware corporation (the "Company"),  of an aggregate of 17,150,000 shares (the
"Registered  Shares") of its Class A Common Stock, par value $.01 per share (the
"Class A Common Stock") and Class B Common Stock,  par value $.01 per share (the
"Class B Common Stock") which underlie options that were, and will be, issued to
purchase  shares of Class A Common Stock and Class B Common Stock of the Company
pursuant to the American  Tower Systems  Corporation  1997 Stock Option Plan, as
Amended and  Restated on April 27, 1998 (as amended,  the  "Plan"),  and options
that were issued to purchase  shares of Class A Common  Stock and Class B Common
Stock of the Company  pursuant to the Exchanged  Option  Agreements with certain
named individuals (the "Exchanged Option Agreements"),  the following opinion is
furnished to you to be filed with the  Securities and Exchange  Commission  (the
"Commission") as Exhibit 5 to the Company's  registration  statement on Form S-8
(the "Registration Statement").

         We have  acted  as  counsel  to the  Company  in  connection  with  the
preparation of the  Registration  Statement,  and we have examined  originals or
copies,   certified  or  otherwise  identified  to  our  satisfaction,   of  the
Registration  Statement,  the  Restated  Certificate  of  Incorporation  of  the
Company,  as amended (the  "Restated  Certificates"),  the Plan,  the  Exchanged
Option Agreements,  corporate  records,  certificates and statements of officers
and accountants of the Company and of public officials, and such other documents
as we have considered  necessary in order to furnish the opinion hereinafter set
forth.  We  express no  opinion  herein as to any laws  other  than the  General
Corporation Law of the State of Delaware. We assume that the number and issuance
of  options  to be  offered  from  time to time  pursuant  to the Plan have been
determined and authorized by proper action of the Board of Directors, or a





American Radio Systems Corporation
May 5, 1998
Page 2

committee thereof, of the Company and that the number,  issuance and sale of the
Registered  Shares to be offered  from time to time  pursuant to the exercise of
such options have been and will be determined  in  accordance  with the Restated
Certificate  and  applicable  Delaware Law. We further  assume that prior to the
issuance  of any  Registered  Shares,  there  will  exist,  under the  Company's
Restated Certificate,  the requisite number of authorized shares of common stock
for  such  issuance  which  are  unissued  and are not  otherwise  reserved  for
issuance.

         Based on and subject to the foregoing, we are of the opinion that, when
the  Registration  Statement has become effective under the Securities Act, upon
due  authorization  by the Board of Directors,  or a committee  thereof,  of the
Company of an issuance of an option  pursuant to the Plan,  and upon an issuance
by the Company of Registered  Shares pursuant to the exercise of such option and
upon delivery of certificates representing the Registered Shares against payment
therefor  in the  manner  contemplated  by the  Plan  and the  Exchanged  Option
Agreements,  the Registration  Statement and any applicable  amendment of either
thereof,  the Registered  Shares  represented by such  certificates will be duly
authorized, validly issued, fully paid and nonasseassable by the Company.

         We hereby  consent to the  filing of this  opinion as an exhibit to the
Registration  Statement. In giving such consent, we do not thereby admit that we
come within the category of persons whose consent is required under Section 7 of
the  Securities Act or the Rules and  Regulations of the Commission  promulgated
thereunder.

                                               Very truly yours,



                                               /s/ Sullivan & Worcester LLP
                                               SULLIVAN & WORCESTER LLP




                                                                    EXHIBIT 23.1


                          INDEPENDENT AUDITORS' CONSENT

         We consent  to the  incorporation  by  reference  in this  Registration
Statement of American Tower Systems  Corporation on Form S-8 of our report dated
March 6,  1998  (except  for Note 4, as to which  the date is March  27,  1998),
appearing  in  the  Annual  Report  on  Form  10-K  of  American  Tower  Systems
Corporation for the year ended December 31, 1997.

         We consent  to the  incorporation  by  reference  in this  Registration
Statement of American Tower Systems Corporation on Form S-8 of our report on the
financial  statements of OPM - USA - INC. dated March 2, 1998,  appearing in the
Current Report on Form 8-K of American Tower Systems  Corporation filed on March
20, 1998.

                                                       /s/ Deloitte & Touche LLP

DELOITTE & TOUCHE LLP
Boston, Massachusetts
May 5, 1998