Kissing The Sky

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In the months right after Sept. 11, when smoke was still rising over the ruins of the Twin Towers, there were people ready to write the obituary for skyscrapers. Tall buildings were too inviting as targets for terrorism, too disruptive to the urban fabric and not even particularly profitable, since so much of the rentable floor space was taken up by elevator shafts. The only clients still interested in building them were in nations that wanted a symbol of their arrival as a contender in the global market, mostly in Asia's Pacific Rim. The honor of having the world's tallest building passed from the U.S. in 1998, when the 1,483-ft. Petronas Towers in the Malaysian capital of Kuala Lumpur overtook the 1,450-ft. Sears Tower in Chicago. And then there is the endlessly ambitious city of Dubai, in the United Arab Emirates, which architecturally is the mouse that roared: in the past five years, three of the world's 25 tallest buildings have been topped off there, and two more are in the works.

But the urge to go higher is as old as the Great Pyramid (482 ft.). Or the Washington Monument (555 ft.). Or the Eiffel Tower (984 ft.). Is Osama bin Laden any match for our deepest impulses? "The skyscraper seems to have even more power now as a symbol of modernization," says Robert A.M. Stern, dean of the school of architecture at Yale University. And from the point of view of environmentalists and regional planners, tall buildings are the best alternative to suburban sprawl and the best means of getting more people and businesses into a smaller footprint on the ground, putting less pressure on whatever stretches of nature remain. "I think the skyscraper is back," says Stern. "But is it back in the same way? No."

What Stern means is that it's not just the silhouettes or the altitude that's changing. After Sept. 11, security and safety became much larger issues in the thinking of architects. More lives might have been saved at the Twin Towers if the plaster-wallboard interiors of the exit stairwells had not collapsed, blocking some exit routes. The Trade Center depended on a complicated structural system of interior and exterior steel columns. Many new towers favor superstrong concrete cores that not only brace more firmly against wind — and at 2,000-plus feet, you don't want to sway much — but also enclose emergency stairwells in solid

concrete as well. Tall buildings are now more likely to have duplicated communications systems: if one goes out in an emergency, another can still transmit directions to people and rescuers inside.

"There's a tremendously heightened sense of structural safety," says Anthony Vidler, dean of architecture at the Cooper Union in New York City. "Structures used to be designed like bridges, perfectly designed to meet the required need, such as getting a person from one side to another. Now we have a lot of redundancy in structures. If one thing fails, then another will hold, and if that fails, another will hold. It's akin to having five or six engines on a jet plane."

Though new American skyscrapers are not going to the same height as the supertalls being built in other nations, more complicated profiles are finally making their way into the U.S. skyline. Calatrava will be building a tower soon in New York City. His plan is for a structure that separates a dozen condos into discrete four-story modules — town houses in the sky. Each apartment is a $30 million, 10,000-sq.ft. package that's separately cantilevered from an 835-ft. central core, then further supported by exposed trusses that attach to steel piers running the full height of the building. The effect is a dynamic oscillation of forms, with alternating voids and volumes, something utterly unlike the inert slab that is the typical tower.