The Willis Tower, built as and still commonly referred to as the Sears Tower, is a 110-story, 442.1 m skyscraper in Chicago, Illinois, United States. At completion in 1973, it surpassed the World Trade Center towers in New York to become the tallest building in the world, a title it held for nearly 25 years and remained the tallest building in the Western Hemisphere until 2014 and the completion of a new building at the World Trade Center site