1. The Willis Tower

2. Design  In 1969, Sears, Roebuck & Co. decided to build the Sears tower in Chicago, Illinois. So they hired Skidmore, Owings and Merrill to build it for them. Chief architect on the project was Bruce Graham, head structural engineer Fazlur Khan.  Their inspiration was to make a giant office to hold all their employees.

3. History  The first steel was put in place in April 1971 and the structure was completed in May 1973.  At the time of its completion, the Sears Tower surpassed the height of New York's unfinished World Trade Center to become the world's tallest building.  Currently, the Sears Tower is the tallest skyscraper in the United States, and the fourth-tallest freestanding structure in the World.

4. Function  The tower was built to house all the 350,000 employees that Sears had in 1969.  It was used as offices for all the Sears employees instead of having a lot of small offices all over Chicago.  Sears has sold the tower to Willis Group Holdings, Ltd. And the name will be changed this month.

5. Looks  The Sears tower is the fourth largest freestanding building in the world an the largest building in the U.S.  On top of the enormous building in Chicago are two giant antennas to pick up television signals.5  Black bands appear on the tower around the 29th– 32nd, 64th–65th, 88th–89th, and 104th–109th floors. These are louvers which allow ventilation for service equipment and obscure the structure's belt trusses.

6. Cost  Construction costs totaled approximately $150 million USD at the time, which would be equivalent to roughly $950 million USD in 2005.

7. Pictures