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
Metropolitan Tower (Chicago) White, the Metropolitan Tower was named the Straus Building when completed in 1924. Though it was the first building in Chicago with 30 or more floors, it was never officially designated Chicago's tallest building since the Chicago Temple Building, also completed in 1924, is taller by but has seven fewer floors. The Straus Building and the Chicago Temple Building were the first to take advantage of the 1923 zoning ordinance; before then, no building in Chicago could be taller than . The Metropolitan Tower was at one time called the Continental National Insurance Company Building (later Continental Center I). From