Rather than an era of architectural modesty, the decade since 9/11 has seen a flowering of skyscraper construction. In the 70 years before 9/11, the record for the tallest building grew 230 feet. Since then, it has shot up 1,234 feet. And it’s poised to rise much higher over the next decade. Today’s tallest skyscrapers are new in every respect: new structures, new materials, designed and tested with new methods. The result isn’t just taller buildings but an entirely new category of building: the supertall skyscraper.