The paradigm of city networks, complementary to the traditional one of urban hierarchy (as epitomised by the ‘central-place’ model) and initially proposed by the southern European tradition of spatial analysis (Dematteis 1985, 1990; Camagni 1993a), has gained interest and support in other scientific and policy contexts, particularly in regional and urban geography (Castells 1996; Malecki 1997; Nijkamp 2003). Currently we speak about ‘city networks’, ‘reti urbane’ and ‘réseaux de villes’ to define new organisational forms of the urban structure and new tools for urban policies. Recently the concept was supported by the EU spatial strategy document, the ESDP-European Spatial Development Perspective, particularly in its Noordwijk (1997) and Glasgow (1998) drafts, but also in its final draft approved in Potsdam by the ministers responsible for spatial planning (EU 1999), in the specification given by this author, namely that of ‘complementarity’ and ‘synergy’ networks.