City Hall Plaza, City Hall Plaza Tower or 900 Elm Street (U.S. Route 3), is a prominent 275-foot (84 m) 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 all New England cities north of Cambridge, Massachusetts. 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. The building is recognizable as one of the main icons of the Manchester skyline, along with the Hampshire Plaza, the Radisson Hotel, the Center of New Hampshire, and the Citizens Bank building. The facade is brick and limestone, with a four-gabled blue roof.