a2006.jan.21

Forbes.com
Home Improvement
World's Tallest Towers 2006
Sara Clemence

Fictional film apes aren't the only creatures drawn to great heights. Human beings have always been looking for ways to escape the ground--by building machines that fly or structures that stretch into the clouds. But many of today's tallest are so high that even King Kong would get vertigo.

When it comes to those buildings, what constitutes "tall" varies from place to place and year to year. The loftiest buildings in Europe are waist-high to those in the New World. Iconic American buildings that once held records have been bumped down by new skyscrapers in Asia--which in coming years will be surpassed by new structures, including the Freedom Tower in New York City, Burj Dubai in the U.A.E., and others still on the drawing boards.

We are building higher and higher, but how high can we go? And how high do we want to?

"I think for a while we will keep building up and up and up," says architect Cesar Pelli, whose projects include the Petronas Towers in Malaysia, currently the second- and third-tallest towers in the world. "The desire is there."

For much of the 20th century, the U.S., the world's economic powerhouse, dominated the skyscraper scene. Steel frames and the invention of elevators combined to made tall buildings achievable, and urbanization made them necessary. Again and again, American buildings topped one another--the Chrysler Buildings was the tallest in 1930 but was overtaken by the Empire State Building a year later. It was surpassed when the World Trade Center arrived on the scene in 1973, but two years later Chicago's Sears Tower became the tallest at 1,454 feet.

The landscape looks very different in the 21st century, with other countries and continents dominating the top of the tallest list.

"We're seeing a tremendous amount of activity overseas, whether it's in Asia or the Middle East," says Ron Klemencic, chairman of the Council on Tall Buildings and Urban Habitat and president of Seattle-based structural engineering firm Magnusson Kelemcic Associates. "For countries that are emerging on the economic scene, very tall buildings are symbols of their economic strength."

The tallest building in the world, Taipei 101, was completed in 2004. It is a national symbol for Taiwan, as are the Petronas Towers for Malaysia. A government plan to bring Malaysia into the developed world by 2020, Klemencic points out, included a scheme to get attention with very tall buildings.

"It seems obvious that what began as kind of an American idea became the emblem of the modern world and modern society, particularly modern capitalist society," says James Sanders, a New York-based architect and author of Celluloid Skyline: New York and the Movies. "It doesn't seem to have lost much of its energy."

Building technology doesn't limit the heights of our skyscrapers, experts say.

"Structure is able to keep up with demands of the developer without any difficulty," observes Leslie Robertson, head of Leslie E. Robertson and Associates and structural engineer for the World Trade Center.

Pelli, for one, believes that the limits are going to come from human psychology and physiology. How long are you willing to be inside an elevator? If we build faster elevators, will we reach a point where pressure changes will be a hazard?

"You may get the bends if you go up or down too fast," Pelli says. "Around 150 stories, that may start happening. We don't know yet. You could pressurize whole buildings, but I don't think people want to live in a sealed building."

Safety is also a factor, of course, especially in the aftermath of the Sept. 11, 2001, terrorist attacks. But, surprisingly, architects and developers continue to push to hold taller and taller towers. At the time of the attack, one of Pelli's towers was under construction in Hong Kong; it took just 20 minutes for his clients to decide to proceed with the project, he says. And the Freedom Tower, which will be built on the World Trade Center site, will be taller than the original complex.

The economics of very tall buildings can be complicated as well. The higher you go, for example, the more elevators you need, Sanders says.

"They keep eating area out of the lower floors," he says. "You get to a point where going taller is not gaining you square footage."

In some places, such as China's increasingly crowded cities, tall may still make sense. "Clearly the skyscraper is the solution to rational living in high-density populations, because it allows people to use mass transit in order to move people around," says Carol Willis, founder and director of the Skyscraper Museum in New York City. But that doesn't hold true across the board.

"In the Middle East, you might scratch your head a little bit," Klemencic says. "The overall populations of countries like Qatar and Dubai are quite low, but you're building super-tall buildings with millions of square feet."

Burj Dubai, however, is more than a skyscraper. The residential and hotel tower, expected to be more than 2,000 feet tall, is part of a complex. "It's the shopping center, golf course and the smaller towers that, in total, make it work economically," Klemencic says. Where tall buildings of the 20th century were primarily office towers, today many of them are mixed-use; part hotel, part condo, part retail and part office space--all in amounts that the local market can absorb.

Prestige, of course, is always a factor for extremely tall buildings--and not just because you can charge more for high-profile buildings. Robertson's firm is working on a 50-floor building in Lahore, Pakistan, where the tallest building might be ten or 12 stories high, he says.

"They become landmarks for high net worth individuals or some of the more significant developers," says Nick Billotti, president of New York-based Turner Construction International, which is owned by Turner Construction. The firm has built many of the best-known skyscrapers, including Chicago's Aon Center and Taipei 101. "They serve as signature buildings for countries."

There is plenty of debate about what makes one building taller than another--should spires be counted or only occupied floors, for example? We used the rankings from Emporis, a real estate information company based in Darmstadt, Germany. The list includes buildings that have reached their full height, even if they are unfinished. They are measured by structural height, which is measured from the base to the "highest architectural or integral structural element of the building." (Spires count, but not antennae.) The list only includes buildings, not communications towers or other structures, which is why Toronto's CN Tower doesn't make the cut, galling as that may be to Canadians.

Still, towering above the rest may not have the same power it once did.

"New York has a media machine that makes things in it famous. Films and postcards and pictures," Sanders says. Not every structure can have a film like King Kong attached to it. "In climbing the Empire State Building, Kong brings it to life."

Ask someone on the street what the tallest building in the world is, and they probably won't know--and may well guess that it is one of those memorable buildings, like the Chrysler or Empire State, which has long since been overtaken.

"How much are they able to capture your imagination and your heart?" Pelli says. "Being tall doesn't necessarily do it.



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