By Gustavo Ambrosini and Guido Callegari

As focus shifts to "no net land take" city regeneration approaches one of the main traditional elements of architecture-the roof-is gaining renewed prominence. This book provides a survey of worldwide experiences of city rooftop re-use strategies such as building-on and integrating new volumes within the existing buildings. Twenty-four case studies illustrate a multiplicity of projects that innovate on traditional typologies by offering multiple ways of living, working and using public services in the city. They all share a symbiotic method that exploits the extraordinariness of the "top condition" offered by the roof to foster a subtle change in the whole building's urban identity.