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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1. Name and Address of Reporting Person * HESS WILLIAM H   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) EVP, Int'l. Operations (Last) (First) (Middle) 116 HUNTINGTON AVENUE 3. Date of Earliest Transaction (Month/Day/Year) 03/10/2011 (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 Class A Common Stock 03/10/2011   M   7,864 A $ 0 10,542 D   Class A Common Stock 03/10/2011   F   2,506 D $ 50.78 8,036 D   Class A Common Stock 03/10/2011   M   5,220 A $ 0 13,256 D   Class A Common Stock 03/10/2011   F   1,658 D $ 50.78 11,598 D   Class A Common Stock               3,662 I By GRAT

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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

$ 50.78

03/10/2011

A

61,368

(1)

03/10/2021

Class A Common Stock

61,368

$ 0

61,368

D

Restricted Stock Units

(2)

03/10/2011

A

20,678

(3)

(3)

Class A Common Stock

20,678

$ 0

20,678

D

Restricted Stock Units

(2)

03/10/2011

M

7,864

(4)

(4)

Class A Common Stock

7,864

$ 0

15,727

D

Restricted Stock Units

(2)

03/10/2011

M

5,220

(5)

(5)

Class A Common Stock

5,220

$ 0

15,657

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
HESS WILLIAM H 116 HUNTINGTON AVENUE BOSTON, MA 02116			EVP, Int'l. Operations

Signatures

/s/ Mneesha O. Nahata, as attorney-in-fact		03/14/2011
**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)	This option was granted pursuant to the 2007 Equity Incentive Plan, and is exercisable in 25% cumulative annual increments beginning March 10, 2012.
(2)	Each Restricted Stock Unit (RSU) respresents a contingent right to receive one share of Class A Common Stock.
(3)	This RSU was granted pursuant to the 2007 Equity Incentive Plan, and vests in 25% cumulative annual increments beginning March 10, 2012.
(4)	This RSU was granted on March 10, 2009 pursuant to the 2007 Equity Incentive Plan, and vests in 25% cumulative annual increments beginning March 10, 2010. This Form 4 reflects the vesting of this RSU on March 10, 2011 as to 50% of the original grant amount.
(5)	This RSU was granted on March 10, 2010 pursuant to the 2007 Equity Incentive Plan, and vests in 25% cumulative annual increments beginning March 10, 2011. This Form 4 reflects the vesting of this RSU on March 10, 2011 as to 25% of the original grant amount.

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