Willis Tower
Willis Tower is seen as the best work of architect Fazlur Khan. As of 2021, it is the third-tallest building in the United States and the Western hemisphere. It is also the 23rd-tallest in the world. Each year, more than one million people visit its observation deck, the highest in the United States. It is one of Chicago's most popular tourist places. The tower was renamed in 2009 after the Willis Group bought the tower.