The Sears Tower is a skyscraper in the city of Chicago, Illinois. The building has been the tallest in North America since 1973, surpassing both the former World Trade Center and Empire State Building. The tower was commissioned by the Sears, Roebuck and Company, and was designed by architect Bruce Graham and engineer Fazlur Khan of Skidmore, Owings and Merrill.
In 1969, Sears and Roebuck was the largest retailer in the world and had some 350,000 employees on the payroll. Company executives decided to consolidate their numerous employees that were distributed all over Chicago, into one structure on the edge of the Loop neighborhood. The space demands required three million square feet and additional room for growth and expansion in the future. The architects, developers and financiers came together and decided on an imposing 55,000 square foot structure and received approval from the Chicago Aviation Board. The entire construction of the tower was paid out of the pocket of the Sears Company and the final costs were estimated to be around $150 million.
Construction of the tower began in August of 1970, with the building reaching its maximum height on May 3rd, 1973. Once it was completed, the structure had 108 stories according to traditional counting standards and according to owners it is 109 stories with the main roof, and 110 with the mechanical penthouse. From the ground to the top floor, the tower measures 1,450.58 feet. The building further increased in height in February of 1982, when two television antennas were added, making its total height 1,730 feet tall.
The Sears Tower is the second tallest free-standing structure in North America, the first being the CN Tower in Toronto, Canada. The black bands that appear on the tower are actually louvers which allows for ventilation for service equipment and to hide the belt trusses, which Sears and Roebuck did not want to be visible, like the ones used on the John Hancock Center.
The observation deck of the Sears Tower opened on June 22nd, 1974 and is on the 103rd floor of the tower. From this vantage point, visitors can view the plains of Illinois, across Lake Michigan, into Indiana, Michigan and Wisconsin on a clear day. The deck is one of the most popular attractions in Chicago and draws some 1.3 million visitors every year.
The top of the tower is the highest point in the state of Illinois and the antennas get struck by lightning on average of 650-675 times per year. The design of the tower was favored because the building can easily be expanded onto with extra height if needed. The Sears Tower Observatory is one of the most visited and highest observatories, and one cannot experience and appreciate the skyline of Chicago until it is viewed from this vantage point.