Willis Tower
In January 2009, work to improve the Skydeck began, such as adding glass balconies that go  outside of the building. The all-glass boxes are called "The Ledge." Visitors can see the street below. The boxes can hold . It opened to the public on July 2, 2009. On May 29, 2014, the laminated glass flooring of one of the boxes broke while visitors were inside. Nobody was hurt. The flooring on that same box cracked on June 12, 2019.