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
Library Tower (Chicago) Library Tower (Chicago) Library Tower Chicago is located on 520 S. State Street, Chicago, Illinois, which is the block directly south of the main branch of the Chicago Public Library in the Loop community area. Currently (4/2009) the building has 184 Units. 52 units have been sold and closed. Another 36 are under contract. Apparently, the building was mostly sold unit the economy forced investors to pull out of the building, leaving it largely unsold. Units have been on sale since 2005, with closing first occurring in 2008. There has been substantial price drops from being on the market (1