The RIMED project deals with three serious and interacting problems of South-Eastern Europe: increasing spatial inequality, serious geographical and economic fragmentation and unbalanced or even anarchic growth of metropolitan areas leading to a further concentration of activities. The latter may lead to traffic congestion, pollution, environmental degradation and social segregation, which threaten to undermine the prospects of large cities for sustainable development. RIMED proposes a development strategy for South-Eastern Europe which is based on transnational networks of co-operation and which promotes polycentric urban development with widespread effects to the hinterlands of the large cities. The project is based on a network of co-operation among four important cities in the region, Sofia, Skopje, Tirana and Thessaloniki, and involves the administrative as well as scientific institutions from these cities.