Chicago Spire would have further transformed the always-growing Chicago skyline. Plans for the tower included 1,193 condominiums with each of the building's 150 stories rotated 2.4 degrees from the one below it for a total 360 degree rotation. In February 2008, prices for the condominiums were announced as ranging from $750,000 to $40 million USD. For supplemental structural support, each floor was to be surrounded by cantilevered corners and four concave sides. Similar to the Willis Tower (formerly Sears Tower) and John Hancock Center observation decks, the Chicago Spire design included a community room on the top floor offering residents a view
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