The Ledge at Skydeck Chicago

Willis Tower, formerly Sears Tower, is the premier corporate office building in Chicago, home to more than 100 companies. The iconic building is the tallest in the Western Hemisphere, ecompassing more than 4.5 million square feet.  Its Skydeck and 103rd floor glass viewing platform, The Ledge, which attract more than 1.3 million visitors every year.

Made of 1.5 inch laminated glass panels hung from a steel frame that rides on rails, the Ledge at Willis Tower is an innovative addition that allows for views in all directions and provide an experience that approximates being suspended in the air. 

via Skydeck Chicago