In the city of Chicago one of the best-known skyscrapers is located: the Willis Tower. It has 108 storeys and was awarded the title tallest building of the world immediately after it had been completed in 1973, which it held for 24 years. It is still the tallest building of the United States.

The modern glass and steel skyscraper was completed in 1973, only two years after the building work had started. The addition of two television antennas in 1982 increased the height of the building to 527m. The name of the building was changed from Sears Tower to Willis Tower in 2009 due to partial leasing by the insurance broker company Willis Group Holdings. Prior to that, the naming rights for the skyscraper lay with Sears, Roebuck & Co, then the largest retailing company worldwide, which used the building in order to have all its offices in the same place. The rest of the building was rented to smaller businesses. Although Sears did not occupy any more office space from 1995 onwards, the name Sears tower continued to be used. After Sears the building’s owner changed several times over rather short periods of time.

One of the Willis Tower’s special features is an observation deck called Skydeck on the 103rd floor which was open to the public one year after the building was officially opened. It has always been very popular with tourists because of the incredible view from the top of the building and the elevators which take only 60 seconds to reach the deck. In 2009 the observation deck was renovated and new retractable glass balconies were added. In the same year, plans were made to paint the building silver in order to improve energy efficiency; the estimated cost of this operation is 50 million dollars.

Like many other tall buildings also the Willis Tower is used by a large number of radio and television broadcasting stations to transmit their programmes. The skyscraper is very popular and was already featured in several movies and TV series. In 1999 a Frenchman climbed to the top of the building only with his bare hands and feet. However, there was also a criminal attempt to destroy the building in 2006.