Willis Tower Chicago

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Willis Tower, previously known as Sears Tower, is a colossal building in Chicago, USA. The tower stands at an impressive height of 1,450 ft (442.1 m) architecturally and 1,729 ft (527 m) including its tip. It boasts of 108 floors, including three basement levels, and a total floor area of 416,000 square meters. Completed in 1973, it's the tallest building in the Americas and Western Hemisphere. In the world rankings by pinnacle height, as of September 2011, Willis Tower ranks seventh after Burj Khalifa, Tokyo Skytree, Abraj Al Bait Towers, Canton Tower, CN Tower, and Ostankino Tower. However, in terms of overall height, the Petronas Twin Towers in Malaysia laid claim to being the world's tallest building in 1998, but different categories of height led to Taipei 101 in Taiwan claiming the title in 2004. In 2007, Burj Khalifa in Dubai took over as the world's tallest, surpassing all previous records. One World Trade Center in New York City is expected to outdo Willis Tower in terms of structural and pinnacle heights upon completion. Initially, the John Hancock Center held the record for tallest building by pinnacle height from 1969-1978, but Sears Tower's two antennas brought its total height to 1,707 ft (520.3 m) in 1982, making it taller than John Hancock Center but not One World Trade Center. In June 2000, an extension of the Sears Tower’s western antenna raised its pinnacle height to 1,730 ft (527 m), allowing it to claim the tallest building title by pinnacle height. The Willis Tower's owners considered painting the structure silver in 2009 to highlight energy efficiency but later dropped the idea. A plan to build a hotel on the north side of Jackson, between Wacker and Franklin, was also proposed, but city zoning restrictions led to its cancellation. Sears' naming rights expired in 2003, but the building retained its Sears Tower name until Willis Group Holdings agreed to lease a portion of the building and obtain naming rights in 2009. The tower was officially renamed Willis Tower on July 16, 2009. In August 2012, United Airlines announced it would move its corporate headquarters to the Willis Tower.