It may be the single most important architectural detail of the last fifty years. Emerging bravely from the glassy sea of Madison Avenue skyscrapers in midtown Manhattan, the open pediment atop Philip Johnson and John Burgee’s 1984 AT&T Building (now the Sony Tower) singlehandedly turned the architectural world on its head. This playful deployment of historical quotation explicitly contradicted modernist imperatives and heralded the mainstream arrival of an approach to design defined instead by a search for architectural meaning. The AT&T Building wasn’t the first of its type, but it was certainly the most high-profile, proudly announcing that architecture was experiencing the maturation of a new evolutionary phase: Postmodernism had officially arrived to the world scene.