Willis Tower KWO39, programmed by the National Weather Service Weather Forecast Office in Chicago, is equipped with Specific Area Message Encoding (SAME), which sets off a siren on specially-programmed weather radios to alert of an impending hazard, such as a tornado or civil emergency. The building has appeared in numerous films and television shows set in Chicago such as "Ferris Bueller's Day Off", where Ferris and company watch the streets of Chicago from the observation deck. The television show "Late Night with Conan O'Brien" introduced a character called The Sears Tower Dressed In Sears Clothing when the show visited Chicago in 2006.
Willis Tower unfinished World Trade Center to become the world's tallest building. The height was restricted by a limit imposed by the Federal Aviation Administration (FAA) to protect air traffic. The financing of the tower was provided by the Sears company. It was topped with two antennas to permit local television and radio broadcasts. Sears and the City of Chicago approved the design, and the first steel was put in place in April 1971. The structure was completed in May 1973. The construction cost about US$150 million at the time, equivalent to $ million in 2019. By comparison, Taipei 101, built in