The Sears Tower, a skyscraper in Chicago, Illinois, has been the tallest building in North America since 1973. It Surpassed the World Trade Center, which itself had surpassed the Empire State Building only a year earlier. Commissioned by sears, Roebuck and Company, it was designed by Chief architect Bruce Graham and structural engineer Fazlur Khan of skidmore, Owings and merrill.
Constuction commended in August 1970 and the building reached its originally anticipated maximum height on May 3, 1973. When completed, the Sears Tower had overtaken the World Trade Center in New York City as the world's tallest building. The tower has 108 stories as counted by standard methods, though the building owners count the main roof as 109 and the mechanical penthouse roof as 110. The distance to the roof is 1450.58 feet (442 m), measured from east entrance.
In February 1982, two television antennas were added to the structure increasing its total height to 1707 feet (520 m). The western antenna was later extended to 1730 feet (527 m) on June 5, 2000 to improve reception of local NBC station WMAQ - TV.
Black bands appear on the tower around the 29th - 32nd, 64th - 65th, 88th - 89th and 104th - 109th floors. These are louvers which allow ventilation for service equipment and obscure the structure's belt trusses which Sears Roebuck did not want to be visible as on the John Hancock Center.
On August 12, 2007, the Burj Dubai in Dubai, United Arab Emirates was reported by its developers to have surpassed the Sears Tower in all height categories.