The Sears Tower is a 108-story, 1,450.58 feet (442 m) skyscraper in Chicago, Illinois. 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.
Currently, the Sears Tower is the tallest skyscraper in the United States, and the fourth-tallest freestanding structure in the world.
Although Sears' naming rights had expired in 2003, it has continued to be called the Sears Tower. However, in March of 2009 London-based insurance broker Willis Group Holdings, Ltd., purchased the building's naming rights. In June 2009 the building will be renamed after the firm.