Immediately after 9/11, there was widespread speculation that the destruction of the World Trade Center heralded the demise of the tall building. Not so. Five years later, skyscrapers continue to be built in cities around the world. Moreover, skyscraper design itself is undergoing a major evolution. The classic towers of the 1920s took their cue from spires and steeples—they stepped back as they rose (the Empire State Building) and ended in a pinnacle (the Chrysler Building). Modernist skyscrapers, such as the boxy Seagram Building, abandoned the steeple model. Postmodern architects resurrected the spire-top, although they usually combined it with a more-or-less standardized shaft, as in the twin Petronas Towers in Kuala Lumpur (at right). But even before 9/11, there were signs that new types of skyscrapers were emerging, neither Modernist boxes nor replays of the spire model.