The John Hancock Center was completed in 1970, and its gently sloping black steel form remains one of the most-recognizable structures in Chicago’s famed skyline. John Hancock Center The John Hancock Center (centre building) on North Michigan Avenue in Chicago. © Chicago Architecture Foundation A bold form was chosen for the Hancock Center. The tapered rectangular tube—with giant trusses on each of the four sides—readily shows how the building is supported.