77 West Wacker Drive, previously the United Building, is an office building in the Chicago Loop. It was finished in 1992. The building rises to a height of 668 ft (204 m) with around of interior space. The building, with 51 floors, was designed by Ricardo Bofill. It was formerly known as the RR Donnelley Building. In 2007, the building became the corporate headquarters of United Airlines.