The Sears Tower is a skyscraper in Chicago, Illinois. Commissioned by Sears, it was designed by chief architect Bruce Graham and structural Engineer Fazlur Khan of Skidmore, Owings, & Merrill. Construction commenced in August 1970, and reached its maximum height on May 4 1973. When completed, the Sears Tower had overtaken the twin towers of the World Trade Center in New York as the world's tallest building. It is normally said to have 110 stories but by some measures has 108. The height of the roof is 1,450 feet (442 m) measured from the main entrance, or 1,454 feet (443 m) measured from the side entrance (both figures are seen in reference books but the Council on Tall Buildings and Urban Habitat uses main-entrance heights). The total height of the structure including the two television antennas on top was 1,707 feet (520 m), until these were later extended to 1,729 feet (527 m) to outstrip the World Trade Center antenna.

At 452 m (1,483 feet) tall, including decorative spires, the Petronas Twin Towers in Kuala Lumpur, Malaysia, laid claim to replacing the Sears Tower as the tallest building in the world in 1997. In the ensuing controversy four different categories were created with the Petronas only taking one of these, however, the re-definition has done little to help. With the arrival of another rule bender, the Taipei 101, the Petronas towers were surpassed in spire height and for the first time the Sears was surpassed in roof height,but the Sears antenna is still taller than the Taipei spire.

Height comparison with other tall buildings

The Sears Tower is the tallest office building in the United States (although the Freedom Tower in New York City plans to exceed the Sears Tower's structural, but not occupied, height by 2008) and it retains the world record when measuring the height from the sidewalk level of the main entrance to the top of antenna. It was unseated for having the highest roof of any building in the world and the highest habitable floor in the world by Taipei 101. In side by side comparisons the Sears Tower still looks the tallest however, and until measurement rules catch up with the reality of design features, the controversy will continue. Buildings are in the works that will soundly surpass the Sears in all height categories, but whether the Taipei or (especially) the Petronas actually earned the title in the interim is controversial.

Without warning, in 1999, French urban climber, Alain "Spiderman" Robert, using only his bare hands and feet and with no safety devices of any kind, scaled the building's exterior glass and steel wall all the way to the top (even in the face of a thick fog which settled in near the end of his climb, making the last 20 floors of the building slippery).

The observation deck on the 103rd floor of the tower is 1,353 feet above ground and is a famous tourist attraction. The tourists can experience how the building sways on a windy day. They can see far over the great plain of Illinois and over Lake Michigan on a clear day.

Despite its higher view, it does not have as good a location as the John Hancock building for Chicago's night scenery and lake views.

New owners purchased the tower in March 2004 and are rumored to intend to rename the building.

See also

• 50 Tallest buildings in the U.S.
• List of towers
• World's tallest structures

External links

• The story of Sears Tower - by CBS Forum
• Structurae: Sears Tower
• Official Sears Tower website