Burj Khalifa with Smith's attempts to make the crown more slender. The building opened on 4 January 2010. The tower was designed by Skidmore, Owings and Merrill (SOM), which also designed the Willis Tower (formerly the Sears Tower) in Chicago and the One World Trade Center in New York City. Burj Khalifa uses the bundled tube design of the Willis Tower, invented by Fazlur Rahman Khan. Due to its tubular system, proportionally only half the amount of steel was used in the construction, compared to the Empire State Building. Khan's contributions to the design of tall buildings have had a profound impact
Randolph Tower Randolph Tower Randolph Tower, formerly known as the Steuben Club Building, is a historic Gothic Revival skyscraper in Downtown Chicago. The building was constructed in 1929 and designed by architect Karl M. Vitzthum, who designed another Chicago landmark, the historic One North LaSalle Building. Randolph Tower was built for the Steuben Club of Chicago to promote German-American heritage. After the first World War, American citizens of German descent sought to found clubs to serve as a testimonial of their loyalty to the ideals of American citizenship. The first 25 floors were built for retail and offices and the club was