Cook County Board of Commissioners in the context of "Chicago City Hall"

The City Hall-County Building, commonly known as City Hall, is a 12-story building in Chicago, Illinois, that houses the seats of government of the City of Chicago and Cook County. The building's west side (City Hall, 121 N. LaSalle St.) holds the offices of the mayor, city clerk, and city treasurer; some city departments; offices of alderpersons of Chicago's 50 wards; and the Chicago City Council's chambers. The building's east side (County Building, 118 N. Clark St.) houses offices of the Government of Cook County, including the Cook County Board of Commissioners' chambers.

The building spans a city block bounded by Randolph Street to the north, Washington Street to the south, Clark Street to the east, and LaSalle Street to the west. It is the seventh building to serve as Chicago's city hall, the fourth built at its location, and the third shared by the governments of Chicago and Cook County. Its location has served as the seat of the city and county governments since 1853, except for a period from 1871—when the Great Chicago Fire destroyed the building—to 1885.