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At 1,454 feet and 110 stories tall, the Willis Tower (formerly known as Sears Tower) was the world’s tallest building from its construction in 1974 until 1998. The stepped-back profile, reminiscent of skyscrapers of the 1920s, is a solution to the engineering challenge of supporting such a tall tower. The building consists of nine separate structural tubes bound together to strengthen the central sections which extend the full height of the tower. Read more:
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, by Jay Pridmore, Chicago Architecture Foundation, published by Pomegranate (2002)
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