City Hall Plaza, City Hall Plaza Tower or 900 Elm Street (U.S. Route 3), is a prominent office tower in Manchester, New Hampshire. Since its completion in 1992, City Hall Plaza has been the tallest building in the city of Manchester, the state of New Hampshire, and northern New England. It is shorter than most of the tallest buildings in Boston, Hartford, New Haven, and Providence. The tower is used for office space for both private businesses and the city of Manchester.