11 Structures that Define America


Sears Tower

In 1969, retail giant Sears, Roebuck and Company wanted to consolidate its employees working in offices around the Chicago area. Designed by chief architect Bruce Graham and structural engineer Fazlur Khan of Skidmore, Owings and Merrill architects, construction on Chicago's Sears Tower began in 1970. The colossal structure opened in 1973, making it the world's tallest building. In 1998, it was surpassed by the Petronas Towers in Malaysia, but it is still the tallest building in the United States. With 110 stories, the distance to the roof is 1,450 feet 7 inches. However, in 1982, two television antennas were added, increasing its total height to 1,707 feet. To improve broadcast reception, the western antenna was extended in 2000, bringing the total height to 1,725 feet. The Skydeck observatory on the 103rd floor can be reached in 45 seconds by an express elevator. At 1,353 feet, sightseers can see Illinois, Indiana, Michigan, and Wisconsin on a clear day.