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
Center City Tower (Philadelphia) with Comcast Corporation, Philadelphia's most high-profile corporation, in mind. Such a rumor would have been killed on January 5, 2005, the day Comcast Center was officially launched. Center City Tower (Philadelphia) Center City Tower was the working name of a formerly proposed skyscraper in downtown Philadelphia. Designed and proposed by the firm now known as KlingStubbins (designers of Philadelphia's Penn Center and Bell Atlantic Tower), the building would have risen to a height of 1,050 feet (320 m) and 75 stories, making it the tallest building in The United States outside New York and Chicago, surpassing the height of the