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
Sears, Roebuck and Company Complex a modillioned cornice. It housed water tanks for firefighting on the upper levels, as well as offices and secretarial training facilities. It also housed the early broadcast facilities for WLS-AM. In 2015, it was refurbished and reopened to the public as the "John D. and Alexandra C. Nichols Tower". It now houses non-profit groups and offices, including a classroom on the 12th floor for the School of the Art Institute of Chicago. The Sears Roebuck plaque is still visible on top of the building. The Sears, Roebuck and Company Administration Building is a broad five-story masonry building, occupying about 3/4