Chicago Many other architects have left their impression on the Chicago skyline such as Daniel Burnham, Louis Sullivan, Charles B. Atwood, John Root, and Helmut Jahn. The Merchandise Mart, once first on the list of largest buildings in the world, currently listed as 44th-largest (), had its own zip code until 2008, and stands near the junction of the North and South branches of the Chicago River. Presently, the four tallest buildings in the city are Willis Tower (formerly the Sears Tower, also a building with its own zip code), Trump International Hotel and Tower, the Aon Center (previously the Standard
Grant Thornton Tower and Exchange Commission filings. Grant Thornton Tower Grant Thornton Tower (formerly Chicago Title & Trust Center, 161 North Clark and sometimes Chicago Title Tower) is an office tower located in Chicago designed by the firm Kohn Pedersen Fox Associates. Before completion in 1990 the twin tower design was awarded The Chicago Athenaeum's "Best Building" Architecture Award, the award was received by one of the lead designers Kevin Flanagan. (view PLP Architects). The fifty-storey building rises 756 feet (230 m) in the Loop and was completed in 1992, on the site of Chicago's Greyhound Bus Station. Previously, a structure at 111