Only by sharing our knowledge, know-how and experiences, we can understand better how social, cultural, economic, political and environmental transformations affect the city of today and how they are likely to affect the city of tomorrow. Only by acting together on the basis of that knowledge and experience, we can redress some of the negative impacts of the process of globalization through a process of global solidarity. For the management of a city to be successful, its policies need to be conductive to "social Sustainability”, means the development which is compatible with the harmonious evolution of civil society, fostering an environment conductive to the compatible contribution of culturally and socially diverse groups while at the same time encouraging social integration with improvements in the quality of life of all segments of the population.