Vertical City (2009) - Chicago’s Sears (Willis) Tower (part 2 of 2) Willis Tower, formerly named Sears Tower, is a 108-story, 1451-foot (442 m) skyscraper in Chicago, Illinois. At the time of its completion in 1974, it was the tallest building in the world, surpassing the World Trade Center towers in New York, and it held this rank for nearly 25 years. The Willis Tower is the tallest building in the United States and the fifth-tallest freestanding structure in the world, as well as the fifth tallest building in the world to the roof. Although Sears' naming rights expired in 2003, the building continued to be called Sears Tower for several years. In March 2009 London-based insurance broker Willis Group Holdings, Ltd., agreed to lease a portion of the building and obtained the building's naming rights.[3] On July 16, 2009, the building was officially renamed Willis Tower. Willis Tower remains the tallest building in the Americas. With a pinnacle height of 1730 feet (527 m), it is the second tallest freestanding structure in the Americas, as it is 86 feet (26 m) shorter than Toronto's CN Tower, and is the only other freestanding structure in the Americas to exceed 1500 feet (457.2 m) in height. As of August 2009, Willis Tower is the fifth tallest freestanding structure in the world (by pinnacle height), after the Burj Khalifa, the Guangzhou TV & Sightseeing Tower, the CN Tower and the Ostankino Tower.