One Sansome Street, also known as Citigroup Center, is an office skyscraper located at the intersection of Sutter and Sansome Streets in the Financial District of San Francisco, California, United States, near Market Street. The 168 m (551 ft), 41 floor, 587,473 sq ft (54,578.0 m2) office tower was completed in 1984.

Beacon Capital Partners is an American real estate investment firm based in Boston, Massachusetts. It was founded in 1998, after Beacon Properties, Inc., Beacon's predecessor, was acquired by EQ Office in a $4 billion transaction. The company focuses on office and life science properties in major markets across the United States. Its European presence formerly included buildings in London, Paris, and Luxemburg.