File:The Ledge, Willis Tower Skydeck, Chicago, Illinois (43391739711).jpg

The Willis Tower observation deck, called the Skydeck, opened on June 22, 1974. Located on the 103rd floor at an elevation of 1,353 feet (412.4 m), it is the highest observation deck in the United States and one of Chicago's most famous tourist attractions. Tourists can experience how the building sways in wind and see far over the plains of Illinois and across Lake Michigan to Indiana, Michigan, and Wisconsin in clear conditions. Elevators reach the top in about 60 seconds, allowing occupants to feel the change in pressure as they ascend. The Skydeck competes with the John Hancock Center's observation floor a mile and a half away but reaching 323 feet (98.5 m) lower. Some 1.7 million tourists visit annually. A second observation deck on the 99th floor serves as a backup. The tourist entrance can be found on the south side of the building along Jackson Boulevard.

In January 2009, a major renovation of the Skydeck was begun, including the installation of retractable glass balconies which extend approximately 4 feet (1.2 m) from the facade of the 103rd floor, overlooking South Wacker Drive. The all-glass boxes, informally dubbed "The Ledge", allow visitors to see the street below. The boxes, which can accommodate 5 short tons (4.5 metric tons), opened to the public on July 2, 2009. On May 29, 2014, the laminated glass flooring of one of the boxes shattered while visitors were inside but there were no injuries. The flooring on that same box shattered on June 12, 2019.

<a href="https://en.wikipedia.org/wiki/Willis_Tower#Skydeck" rel="noreferrer nofollow">en.wikipedia.org/wiki/Willis_Tower#Skydeck</a>