The world's tallest building for 30 years, from 1974 to 2004 when it was eclipsed by Taiwan's Taipei 101, the Sears Tower in Chicago stand 1,450 feet tall (442m). It's antennas, which are lighted in different colors for various holidays, reach 1,730 feet (527m) into the air, more than half a kilometer and a third of a mile into the sky. While no longer the world's tallest, the Sears Tower still dominates the Chicago skyline. It's a full 300 feet taller than the city's second highest, the 1,136 foot (346m) tall Aon Center, located just a mile east. With 4.6 million square feet of total space, the Sears Tower is the single largest privately owned office building in the world, second overall only to the 9 million square foot Pentagon in Arlington, Virginia.

    Built for the department store owner Sears Roebuck and Company, the 108 floor tower was design by Pakistan-born structural engineer Fazlur Kahn and architect Bruce Graham (both of which ) of the architectural firm Skidmore, Owings and Merril. These same individuals also  designed the 100 floor John Hancock Center, Chicago's other landmark supertall skyscraper. It was Khan who came up with the revolutionary bundled tube structural system used in the tower, in which 9 independent modules are fused together to make one large "super-module." Two of the modules rise to the 49th floor, two more reach the 67th floor, three drop-off at the 90th floor and the remain two go all the way to the top.

    While no longer the headquarters of Sears, the tower is home to major financial and insurance institutions as well as some of the most prestigous law firms in the United States. It is home to a major conference center on the 66th and 67th floor, an event space on the 99th floor and televsion broadcast facilities on the top floors. Just below the broadcast station is the world famous 103rd floor Skydeck. From a perch 1,353 feet in the air, you can see not only the entire city of Chicago, but on a clear day, four states.