Which Chicago skyscraper has an observation attraction called The Ledge?

Chicago’s Willis Tower has an observation attraction called The Ledge.

The Ledge consists of glass balconies extending from the Skydeck on the tower’s 103rd floor. Visitors can stand above the city and look through transparent floors and walls toward the streets below.

The skyscraper was completed in 1973 and was designed by the architectural firm Skidmore, Owings & Merrill. It uses a bundled-tube structural system made from nine connected square tubes.

The building was officially renamed Willis Tower in 2009, although many Chicagoans still use its former name, Sears Tower. The Ledge belongs to the Skydeck visitor attraction rather than being a separate observatory building.