Willis Tower, formerly named Sears Tower, is a 108-story 1,450 feet (442 m) skyscraper in Chicago, Illinois. This tallest skyscraper in the United States has four glass box viewing platforms. These balconies are suspended 1,353 feet (412 m) in the air on the 103rd floor. As per reports, the inspiration for The Ledge came from hundreds of forehead prints visitors left behind on Skydeck windows every week. Skidmore, Owings and Merrill, the architecture firm that designed the tower, also designed this balcony.