Developers: • Sears Roebuck & Co. • The Blackstone Group LP
• Originally the Willis Tower was going to be two twin towers occupying the site at half the height of the current tower.
• When completed as the Sears Tower in 1973 it surpassed One World Trade Center in New York City, completed earlier that year as the World’s Tallest Building. It stayed the WTB from 1973 to 1996, where the Petronas Towers in Malaysia surpassed it, although this was only possible because of the spires atop the buildings, counting by roof height the Willis Tower remained the tallest until 2003 when Taipei 101 in Taiwan was completed, 19 feet taller than the Willis Tower’s roof.
• The building's structure is a "bundled tube" system of nine squares with sides of 75 feet (for an overall width of 225 x 225 ft btw. exterior column lines and 229' at outside faces). Height to width ratio is 6.45:1. The tower was completed for $160 Million and used 76,000 tons of steel, 72,000 cubic yards of concrete, 17,500 tons of mechanical equipment. At peak construction, over 2,400 workers were on site representing 60 different subcontractors. There are 76 single-deck elevators in addition to 14 double-deck elevators, bringing the total to 104 cabs. Other impressive quantities include 25,000 miles of plumbing and 2,000 miles of electrical wire.
• The building has been climbed up twice, by Dan Goodwin in 1981 and by Alain Robert in 1999.
• Sears is no longer headquartered in this building, having sold the building and moved out to Hoffman Estates, Illinois in 1992.
• The "Skydeck Pavilion" entrance on Wacker Drive was added in 1985, the large antennas in 1982, and the 4 HDTV antennas in 1999 (or thereabouts). Extra height was added to the western antenna on 5th June 2000.
• The Willis Tower has become one of America’s most iconic skyscrapers, appearing in several movies, books, and television shows since its completion in 1973.
• The building was officially renamed the Willis Tower on July 16, 2009, after a London-based holdings firm retained the naming rights along with leasing space on multiple floors within the building.
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