AbstractThe European Union has allocated a considerable part of cohesion-policies funds to urban development, recognising urban areas as key-components for social and economic development. They represent at the same time the engine of economy and the social unrest - such as poverty, unemployment and exclusion - the environmental concerns - such as pollution, resource management, urban planning to the maximum extent. Hence there is the need of a sustainable, functional and flexible urban approach to the development, which can meet the different local needs, overcoming metric definitions to classify the manifold connotations of urban agglomerations, characterized by a close network of formal, informal, concrete and virtual relations extending beyond geographic and administrative boundaries to reach an easy territorial management according to the principle of a variable geometry. Only taking up the challenge of an integrated approach, in order to realize a smart sustainable and inclusive society, the European urban network can become a catalyst of innovation and creativity. The Metropolitan City plays a primary role in terms of attractiveness and allocation of resources for development. It can also be a suitable reference framework for the economic recovery with the aim of defining and address the development in relation to the typical features in order to make it competitive both at national and international level.