Boston Properties has acquired the 62-storey John Hancock Tower and Garage in the US state of Massachusetts for $930m.
The firm acquired the tower from a partnership between Normandy Real Estate Partners and Five Mile Capital Partners.
The company will pay $289.5m in cash and is assuming $640.5m in debt as part of the deal.
The transaction is expected to close in the fourth quarter of 2010, according to the Associated Press.
The tower, which is the tallest in Boston, was designed by architectural firm Pei Cobb Freed & Partners and completed in 1976.