After the terrorist attacks that brought down the twin towers in Manhattan, many said it was the end of an era for skyscrapers. New York City proved them wrong. The building constructed to replace the towers, 1 World Trade Center, has risen above 1,250 feet and surpassed the Empire State Building as the tallest in New York.
David Childs, the lead architect and designer of 1 World Trade Center, was involved in the construction of several megastructures around New York. "There was a real void in the sky that was formed when the buildings came down," he tells NPR's Neal Conan. "We have learned a lot from the lessons of 9/11 to make buildings better. But I think that as far as the image of the city, it's always been there. ...
"They're fascinating. And they really do make the image of a city, which we all, I think, respond well to."
From lower Manhattan to Dubai, Kuala Lumpur to Shanghai, buildings continue to reach ever higher. Originating in Chicago in the 1890s, skyscrapers push the limits of gravity and human ingenuity, and countries around the world battle for the rights to the tallest building.
Childs explains the challenges of constructing New York's tallest building, and why we're so fascinated by skyscrapers.
On why we love skyscrapers
"It's, I believe, in our DNA to want to congregate as people. People want to get together, whether it's for worship or marketplace or for business, commerce. And downtown certainly has had commerce and financial activities at its core ever since its beginning.
" ... And so you have to push buildings up to be able to get that density. As a result, it's actually one of the most efficient, environmentally sound constructions because you have so many people working and living exactly where all the infrastructure has been put."
On the design of skyscrapers
"The tall buildings really are unique ... They're not just high rises. They really are skyscrapers, and you have to design them very carefully ... The big force is wind, it's the overturning moment. If you think about a sailboat, it catches the wind and it wants — it leans over. That mast dips off of a perpendicular.
"... In a tall building, which is very slender, you can't sort of spread its legs like one human being would to withstand a horizontal force. So you have to design them, and in this case it's bolted down to actually the most wonderful base, which is that enormous great shift of granite that goes underneath all of New York. And so it's pretty firm and pretty fixed and very robust."
On constructing 1 World Trade Center
"All of the steel and the concrete that goes into it, let alone the skin and then finally the tenant and all the furniture that will be in there, it's an enormous, enormous load. There's about 80 feet between grade and the rock. And in that, interesting enough, right underneath these very tall buildings goes the PATH train, which is the train that takes commuters from New York to New Jersey. And it's not only going through, but it's curving at that point, so technically it was very difficult to do.
"But in that space, it was empty before because they had built what they called the bathtub to keep out the Hudson River. This building is in the Hudson River. It just happens to be, you know, decked over and fill put in place. But it was originally not till you got up to Greenwich Street that the lapping waves of the edge of the river occurred. So it was very, very complicated to be able to build it all, get down there, tie it to the base and then begin construction from grade up. That was relatively simple because it's quite repetitive as you go up."