The introduction of vegetation in urban areas, through both green roofs and green walls, is a sustainable strategy for improving the environment and the quality of life, as well as crucial for urban biodiversity since the moment it is able to create new habitats for plant and animal species. The design and realization of green roof systems abroad is promoted and stimulated while in Italy, this subject, is still an innovation not supported by many real implementations. The application of this technological green system has a great importance for the redevelopment of existing building heritage, especially for historic buildings, to improve their energy-performance qualities, with respect for their architectural value. The aim of this study is to identify the technical issues for the realization of green roofs in urbanized contexts by focusing on the implementation of a green roof on a building of Leghorn following intervention guidelines developed. This research shows that not only does this system allow higher energy saving, but it also brings a decrease of load bearing on the structure.