Like all great artists, Frank Lloyd Wright loved to break his own rules. When he designed the Price Tower (built 1956), Wright was already the master of a language that anchored ground-hugging roofscapes hovering over shadowed spaces which were anchored in vertical elements like chimneys. Wright used Price Tower to explore how this scheme could work in the skyscrapers of the future. The 221ft-high tower, modelled on the structure of a tree, has four vertical elevator cores from which the 19 floor slabs cantilever out. The lightweight &lsquowalls&rsquo (early versions of the curtain walls of today) hung from the floorslabs like leaves on branches. What results is a very special expression for the tall building form, very different from the tall glass box that was being invented at that very time in other cities in America. Wright&rsquos ambition can be judged from the fact that the year Price Tower was built, he proposed a visionary design for a mile-high skyscraper to be built in Chicago &mdash they are only halfway there in Dubai right now. See www.pricetower.org.