Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
MOSKOWITZ STEVEN J
   2. Issuer Name and Ticker or Trading Symbol
AMERICAN TOWER CORP /MA/ [AMT] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
President, U.S. Operations
(Last)
(First)
(Middle)
116 HUNTINGTON AVENUE		 3. Date of Earliest Transaction (Month/Day/Year)
12/29/2006
(Street)

BOSTON, MA 02116		 4. If Amendment, Date Original Filed(Month/Day/Year)
 6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)		 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)		 4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)		 5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)		 6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)		 7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)		 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)		 5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)		 6. Date Exercisable and Expiration Date
(Month/Day/Year)		 7. Title and Amount of Underlying Securities
(Instr. 3 and 4)		 8. Price of Derivative Security
(Instr. 5)		 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)		 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)		 11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Option to Purchase Class A Common Stock $ 3.04 12/29/2006   D(1)     150,000   (2) 12/09/2012 Class A Common Stock 150,000 (1) 0 D  
Option to Purchase Class A Common Stock $ 3.6 12/29/2006   A(1)   150,000     (2) 12/09/2012 Class A Common Stock 150,000 (1) 150,000 D  
Option to Purchase Class A Common Stock $ 21.13 12/29/2006   D(3)     35,000   (4) 06/22/2008 Class A Common Stock 35,000 (3) 0 D  
Option to Purchase Class A Common Stock $ 25.75 12/29/2006   A(3)   35,000     (4) 06/22/2008 Class A Common Stock 35,000 (3) 35,000 D  
Option to Purchase Class A Common Stock $ 23.75 12/29/2006   D(3)     75,000   (5) 12/01/2008 Class A Common Stock 75,000 (3) 0 D  
Option to Purchase Class A Common Stock $ 25.75 12/29/2006   A(3)   75,000     (5) 12/01/2008 Class A Common Stock 75,000 (3) 75,000 D  
Option to Purchase Class A Common Stock $ 23.81 12/29/2006   D(3)     60,000   (6) 11/11/2009 Class A Common Stock 60,000 (3) 0 D  
Option to Purchase Class A Common Stock $ 53.62 12/29/2006   A(3)   60,000     (6) 11/11/2009 Class A Common Stock 60,000 (3) 60,000 D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
MOSKOWITZ STEVEN J
116 HUNTINGTON AVENUE
BOSTON, MA 02116		       President, U.S. Operations  

Signatures

 /s/ Nathaniel B. Sisitsky (as attorney-in-fact)   01/02/2007
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) On December 29, 2006, pursuant to a tender offer conducted by the issuer, the reporting person voluntarily amended an option granted December 9, 2002 to increase the exercise price from $3.04 to $3.60. For Section 16(a) purposes, the reporting person is reporting this amendment as a cancellation of the original option and the grant of a replacement option. The reporting person received no consideration in connection with this amendment.
(2) This option was granted pursuant to the 1997 Stock Option Plan, as amended, and is exercisable in 25% cumulative annual increments beginning December 9, 2003.
(3) On December 29, 2006, the reporting person voluntarily amended an option granted June 22, 1998 to increase the exercise price from $21.13 to $25.75, an option granted December 1, 1998 to increase the exercise price from $23.75 to $25.75, and an option granted November 11, 1999 to increase the exercise price from $23.81 to $53.62. For Section 16(a) purposes, the reporting person is reporting these amendments as a cancellation of the original option and the grant of a replacement option. The reporting person received no consideration in connection with these amendments.
(4) This option was granted pursuant to the 1997 Stock Option Plan, as amended, and is exercisable in 20% cumulative annual increments beginning June 22, 1999.
(5) This option was granted pursuant to the 1997 Stock Option Plan, as amended, and is exercisable in 20% cumulative annual increments beginning December 1, 1999.
(6) This option was granted pursuant to the 1997 Stock Option Plan, as amended, and is exercisable in 20% cumulative annual increments beginning November 11, 2000.

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