Modern Marvel -1

Just watching the history of Sears Tower on the Modern Marvels in History Channel. The facts behind one of the worlds tallest building which is located at chicago are mind blowing. When it was completed in 1973, it was the tallest building in the world. It was primarily built in response to the interior space requirements of Sears & Reobuck - the number one retailer in US. 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.
Some of the facts about Sears tower --

The Sears Tower covers two city blocks and has 101 acres (4.4 million square feet) of office and commerical space.

The roof rises a quarter 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 million cubic feet of concrete -- enough to build an eight-lane highway five 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. Each is securely 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.