American Tower Corporation is a publicly held company (nyse|AMT) that is a leading owner and operator of wireless and broadcast communications sites in North America. The company was formed in 1995 as a unit of American Radio Systems, and was spun off from that company in 1998 when that company merged with CBS Corporation. Today American Tower owns and operates over 30,000 sites in the United States, Mexico, Brazil and India. Headquartered in Boston, Massachusetts, American Tower has local offices nationwide.  Wikipedia