Recent crises show the weakness of global equilibrium stability and manages to change economic and social relations with consequences all over the world. Today, western cities must deal with new problems and with those of the past that have not yet been solved. Innovations in technology, economy, society, and the come up of the climate change are leading to different and not easily predictable evolution of cities. This thesis aims to analyze the main examples of "Green Belts" and look for parallelism, similarities, and differences between the existing plans and the one designed for the city of Rivoli. Preliminary surveys have been conducted, revealing a territory that has been plagued for decades by sprawl, little attention to cultural heritage and the environment caused by the rapid and poorly planned expansion.