The Willis Tower (formerly named and still commonly referred to as Sears Tower) is a 108-story, 1,451-foot (442 m) skyscraper in Chicago, Illinois, United States. At the time of its completion in 1973, it was the tallest building in the world, surpassing the World Trade Center towers in New York, holding this rank for nearly 25 years. Willis Tower is the second-tallest building in the United States and the eighth-tallest freestanding structure in the world. The skyscraper is one of the most popular tourist destinations in Chicago, and over one million people visit its observation deck each year. Named the Sears Tower since its opening, the structure was renamed in 2009 by the Willis Group, as part of their lease on a portion of its space. Its 3D modelled version is made from paper and EPS foam board. It is easy to put together, without the use of any tools and glue. No of Pieces:51 pc. Model Size: 26cm x 19cm x 63.5cm. Age: 8+ years.