Sears Tower (Willis Tower)

Historically Named: Sears Tower
Current Name: Willis Tower
Location: Chicago, Illinois, USA
Architect: Bruce Graham, Skidmore, Owings and Merrill (SOM)
Year: 1973
Height: 442 meters / 1,450 feet
Stories: 110

About the Sears Tower

To provide stability against high winds, architect Bruce Graham used a new form of tubular construction for Sears Tower. Two hundred sets of bundled tubes were laid into the bedrock. Then, 76,000 tons of prefabricated steel in 15-foot by 25-foot sections were put into place. Four derrick cranes moved higher with each floor to lift these steel "Christmas Trees" into position.

Facts about the Sears Tower:

• The Sears Tower covers two city blocks and has 101 acres (4.4 million square feet) of space.
• The roof rises 1/4 of a mile - 1,454 feet (442 meters).
• Its highest occupied floor is 1,431 feet above the ground.
• The foundation and the floor slabs have some 2,000,000 cubic feet of concrete - enough to build an eight-lane highway 5 miles long.
• The Tower has more than 16,000 bronze-tinted windows and 28 acres of black duranodic aluminum skin.
• The 222,500-ton building is supported by 114 rock caissons socketed into the bedrock.
• A 106-cab elevator system (including 16 double decker elevators) divides the Tower into three separate zones with skylobbies in between.
• Two domed entrances, one with skylights, were added in 1984 and 1985.
• The Ledge was added 2009.
• As part of a rental deal, Willis Group Holdings, Ltd. renamed the Sears Tower in 2009.

Architect Bruce Graham talks about Sears Tower:

"The stepback geometry of the 110-story tower was developed in response to the interior space requirements of Sears, Roebuck and Company. The configuration incorporates the unusually large office floors necessary to Sears' operation along with a variety of smaller floors. The building plan consists of nine 75 x 75 foot column-free squares at the base. Floor sizes are then reduced by eliminating 75 x 75 foot increments at varying levels as the tower rises. A system of double-deck express elevators provides effective vertical transportation, carrying passengers to either of two skylobbies where transfer to single local elevators serving individual floors occurs."
-from Bruce Graham, SOM, by Stanley Tigerman.

Plans for the Sears Tower may be seen in Form Follows Finance: Skyscrapers and Skylines in New York and Chicago by Carol Willis (compare prices).

Learn More:

• Skidmore, Owings and Merrill (SOM)
• Bruce Graham
• Architecture in Chicago