Chicago City Hall is the official seat of government of the City of Chicago in Illinois, United States. Adjacent to the Richard J. Daley Center and the James R. Thompson Center, the building that includes Chicago City Hall houses the offices of the mayor, City Clerk, and city treasurer of Chicago; some city departments; aldermen of Chicago's various wards; and chambers of the Chicago City Council on the west side of the building. The building's east side (called the County Building) is devoted to the various offices of Cook County. Situated on a city block bounded by Randolph, LaSalle, Washington, and Clark streets, the 11-story structure was designed by the architectural firm Holabird & Roche in the classical revival style. The building was officially dedicated on February 27, 1911.

Chicago City Hall's entrance features four relief panels sculpted in granite by John Flanagan. Each of the panels represents one of four principal concerns of city government: playgrounds, schools, parks, and water supply. As visitors enter the building, they are greeted with elaborate marble stairways and bronze tablets honoring the past city halls of Chicago from 1837 to the present. The first major renovation project undertaken was in 1967 as major city departments, originally located outside Chicago City Hall, were moved in.

In 2001, the roof gardens were completed serving as a test for the impact green roofs would have on the heat island effect in urban areas, rainwater runoff, and the effectiveness of differing types of green roofs and plant species for Chicago's climate. Noted "green" architect William McDonough designed the project, which is open to the public in the summer.

en.wikipedia.org/wiki/Chicago_City_Hall