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
Chicago Water Tower Louisville Water Tower in Louisville, Kentucky. The Chicago Water Tower now serves as a Chicago Office of Tourism art gallery known as the City Gallery in the Historic Water Tower. It features the work of local photographers and artists, and filmmakers. The tower, built in 1869 by architect William W. Boyington from yellowing Lemont limestone, is 182 feet (55 m) tall. Inside was a 138-foot (42 m) high standpipe to hold water. In addition to being used for firefighting, the pressure in the pipe could be regulated to control water surges in the area. Together with the adjacent Chicago Avenue