Chicago Architecture Center Board of Trade, the Marquette Building, the Monadnock Building, and Daniel Burnham and John Wellborn Root's Rookery among many others. Some modern buildings that are explored include the Sears Tower, John Hancock Center, Mies van der Rohe's Chicago Federal Center and the Trump Tower. The CAC also offers tours of parks and public spaces such as Millennium Park, Maggie Daley Park and the Chicago Pedway. During the summer months, the CAC offers tours of various neighborhoods throughout Chicago in addition to downtown tours. The CAC's most popular tour, the CAFC River Cruise aboard Chicago's First Lady Cruises has departures April–November
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