Look from Sears tower known as Willis Tower

Willis Tower, formerly named Sears Tower, is a 108-story 1,450 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.

As of July 2009, Willis Tower is the tallest building in the United States and the fifth-tallest freestanding structure in the world.

Although Sears’ naming rights expired in 2003, the building continued to be called Sears Tower for several years. However, in March 2009 London-based insurance broker Willis Group Holdings, Ltd., agreed to lease a large portion of the building and as part of the agreement obtained the building’s naming rights. On July 16, 2009, at 10:00 am, the building was officially renamed Willis Tower, upsetting many residents of Chicago.As of July 22, 48,629 people had signed a petition to officially rename the tower the Sears Tower.

Willis Tower remains the tallest building in the Americas, and retains the world record when measuring from sidewalk level of the main entrance to the top of the antenna. 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 1640 feet (500 m) in height. As of July 2009, Willis Tower is the fourth tallest freestanding structure in the world (by pinnacle height), after the Burj Dubai, the CN Tower and the Ostankino Tower.