Willis Tower - Wikipedia

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File:Willis Tower East.JPG - Wikimedia Commons

Willis Building (London) - Wikipedia

The Willis Tower stands in Chicago on March 31, 2011. Formerly named the Sears Tower, the structure was the world's tallest building from its construction in 1974 until 1998. UPI/Brian Kersey Stock Photo - Alamy

File:Willis Tower Chinatown.jpg - Wikipedia

Restren:2011-08-07 2000x3000 chicago from skydeck.jpg - Wikipedia

Sears (Willis) Tower, Chicago Skyscraper

Willis Tower - Wikipedia

Skydeck Chicago - Willis Tower Reviews

File:Chicago (ILL) Willis Tower ( Ex. SEARS Tower ) 1974 longue vue (4800110917).jpg - Wikimedia Commons

Sears Tower, The Racing Madness Wiki