77 West Wacker Drive, previously the United Building, is an American office building in the Loop, Chicago. Finished in 1992, the building rises to a height of 668 ft with around 944,000 square feet (87,700 m2) of interior space. The building, with 51 floors, was designed by Ricardo Bofill Taller de Arquitectura. It was formerly known as the RR Donnelley Building when RR Donnelley was the primary tenant. RR Donnelley moved its corporate headquarters to a different location in May 2005, and in 2007 the building became the corporate headquarters of United Airlines. The deal included naming rights to the building.