BUILDING BIG: Databank: Sears Tower

The Sears Tower is an example of the revolutionary bundled-tube structural design. Tube buildings gain most of their structural support from a rigid network of beams and columns in their outer walls. The rigid outer walls act like the walls of a hollow tube. The Sears Tower is actually a bundle of nine tubes, and is considered one of the most efficient structures designed to withstand wind. This is a great design for a skyscraper in Chicago, the "Windy City," where the average wind speed is 16 miles per hour. As the building climbs upward, the tubes begin to drop off, reducing the wind forces on the building. The Tower's heavy weight -- more than 440 million pounds -- is also supported by 114 piles sunk deep into the earth so that they stand firmly on hard, solid bedrock.

In 1974, the Sears Tower in Chicago assumed the coveted title of world's tallest building, at 1,454 feet. It held this title for 22 years until 1998, when the decorative spires atop the Petronas Towers in Malaysia surpassed the Sears Tower by 33 feet. Today, the Sears Tower still boasts the tallest occupiable floor and the tallest skyscraper roof in the world.

Fast Facts:

The Sears Tower contains enough concrete to build an eight-lane, five-mile-long highway, enough steel to build 50,000 automobiles, and enough telephone wiring to wrap around the world 1.75 times.
On a clear day, you can see four states -- Illinois, Indiana, Wisconsin, and Michigan -- from the Sears Tower Visitor Skydeck.
At the very top of the building, the maximum wind drift is just one foot.
Six roof-mounted robotic window-washing machines clean all 16,100 windows on the Sears Tower.