The Willis tower is located in Chicago, USA. It stands at an impressive 442 meters tall and has 108 stories. When it opened in 1973 it was the tallest building in the world, surpassing the world trade center in New York that had been built two years earlier. Also, at the opening, it was named the Sears Tower which and it was renamed recently (2009) to the Willis Tower. It cost $150 million 1973 US dollars equivalent to $790 million 2013 dollars. It was surpassed by height by the petronas twin towers in Indoneisa in 1998. Today it is the 11th tallest building in the world.