The Willis Tower from the Chicago River. At one time, the Willis Tower (originally the Sears Tower) was the tallest building in the world. However, it is now dwarfed by the Burj Khalifa in Dubai.

The Willis Tower from the Chicago River. At one time, the Willis Tower (originally the Sears Tower) was the tallest building in the world. However, it is now dwarfed by the Burj Khalifa in Dubai.