Completed in 1996 in Kuala Lumpur, Malaysia, the 88-story Petronas Twin Towers soar 451.9 meters, or about 1483 feet, from the ground to the tips of their spires. A fireproof sky bridge joins the two buildings at their forty-first and forty-second floors. Together, the two towers boast nearly as much floor space as covered by 100 football fields.
The planning required for skyscrapers such as the Petronas Towers is very detailed. The foundation and lower stories must sustain incredible loads to support the upper stories. Skyscrapers must also weather tremendous forces from the wind without excessive swaying. Doubling the height of a building increases its sway 16-fold if it is not stiffened. Planners must also make sure that water, electricity, communications, and environmental systems will work properly for all floors. Simply getting water to the top of a skyscraper requires powerful pumps. And then there is the challenge of designing high-speed elevators that efficiently shuttle people up and down a building without taking up too much of its space.
Upon their completion, the Petronas Towers became the tallest skyscrapers in the world-at least according to some authorities. Many people look to the standards set by the Council on Tall Buildings and Urban Habitat (CTBUH) to decide which buildings are the tallest, but even the Council has different categories. One problem is that many skyscrapers have communications antennas placed on top. These are not usually counted as part of the height, since they are not considered part of the structure itself. On the other hand, spires that are part of a building's architectural features, such as that on the Chrysler Building, completed in New York City in 1930, are usually included as part of the building. Chicago's 110-story Sears tower, completed in 1973, easily has the highest occupied floor, at about 436 meters, or 1431 feet. It is also the tallest building to the top of its roof, at 442 meters, or 1450 feet. But the Sears tower has no spire. Its antennas reach over 520 meters (over 1700 feet), above the ground, but again, antennas are not usually counted.
At any rate, the Sears versus Petronas debate may not last long. The spire of the International Financial Center in Taipei, Taiwan may top out at about 508 meters (1667 feet) sometime in 2003. And there are taller buildings to come. Some plans for the proposed Grollo Tower in Melbourne, Australia call for a 560-meter (1838-foot) skyscraper. The proposed Kowloon MTR Tower in Hong Kong could top out at 574 meters (1883 feet). There are also other possible contenders for the title of "World's Tallest" in places as varied as São Paulo, Brazil, Chicago, United States, Shanghai, China, and Jabalpur, India.
You can get more information about the world's tallest buildings at the following sites:
The World's Tallest Building, Media, Inc.
The Greatest Buildings Collection