East Cambridge is a neighborhood of Cambridge, Massachusetts. East Cambridge is bounded by the Charles River and the Charlestown neighborhood of Boston on the east, the Somerville border on the north, Broadway and Main Street on the south, and the railroad tracks on the west. Most of the streets form a grid aligned with Cambridge Street, which was laid out to directly connect what is now the Charles River Dam Bridge with what in 1809 was the heart of Cambridge, Harvard Square. The northern part of the grid is a roughly six by eight block residential area. Cambridge Street itself is retail commercial, along with Monsignor O'Brien Highway, the Twin Cities Plaza strip mall, and the enclosed Cambridgeside Galleria. Lechmere Square is the transportation hub for the northern side. The southern half of the grid is largely office and laboratory space for hundreds of dot-com companies, research labs and startups associated with MIT, biotechnology firms including Genzyme, Biogen and Moderna, the Athenaeum Press Building, light industry, an NRG Energy power station, and various small businesses. This half of the neighborhood is generally identified with Kendall Square. Along the waterfront are several hotels and taller apartment buildings.