Sears Tower - Chicago, Illinois

Sears Tower - Chicago, Illinois - Once the world’s tallest building (now edged out by another in Malaysia However, plans to add an extra 22 feet to one of its twin broacast antennas may put the Tower back in the lead.), the 110-story Sears Tower continues to impress with its steel frame covered in black aluminum and bronze-tinted glass. On clear days, you can see Indiana, Michigan and Wisconsin from the 103rd floor Skydeck open 365 days.

To provide stablity against high winds, architect Bruce Graham used a new form of tubular construction. 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.

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.

Two domed entrances, one with skylights, were added in 1984 and 1985.

Location: 233 S. Wacker Dr, Chicago, IL