Willis Tower . In 1982, two antennas were installed on top of the Sears Tower which brought its total height to , making it taller than the John Hancock Center but not One World Trade Center. However, the extension of the Sears Tower's western antenna in June 2000 to allowed it to just barely claim the title of tallest building by pinnacle height. On May 25, 1981, Dan Goodwin, wearing a homemade Spider-Man suit while using suction cups, camming devices, and sky hooks, and despite several attempts by the Chicago Fire Department to stop him, made the first successful outside ascent of
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