The European Union consists, at present, of a territory of 27 countries. The European Union now comprises approximately 490 million people, living on some 4.3 million square kilometres. Around 70 major cities, with more than 500,000 inhabitants and 20% of the EU 27 population, are part of the European spatial system. Europe has a very imbalanced territorial structure. Looking at the territory of the 27 current EU member states, around 32% of the citizens live and work in a core area shaped by the "Pentagon" London, Paris, Munich, Milan and Hamburg. This Pentagon covers approximately14 % of the EU-27 territory but counts for 46,5% of the EU-27 GDP. The lack of balanced and inefficient sustainable structure of the European territory has been on the political agenda since 1999. In 2005, the European Council stated that Europe must renew the basis of its competitiveness, increase its growth potential and its productivity, and strengthen social cohesion, placing the main emphasis on knowledge, innovation and the optimization of human capital. Although spatial planning (or ‘territorial planning’) as such is not addressed in any of Europe’s Treaties, almost all policy directives have direct or indirect physical effects in our urban and rural environments. ‘Territorial cohesion’ adds to economic and social cohesion by translating the fundamental EU goal of a balanced competitiveness and sustainable development into a territorial setting. Considered in the light of the Lisbon strategy for sustainable economic growth, the key challenge for strengthening territorial cohesion implies enhancing the territorial ‘capital’ and potentials of all EU regions. Stadslab European Urban Design Laboratory is a response to these observations and aims to answer to the double aims of EU territorial cohesion policy and ‘permanent education’ for professionals. The aim of Stadslab is to research the highly dynamic spatial developments at Europe’s fringes, by meeting the new neighbours. To consider what continued enlargement, or the lack thereof might mean, in the European context, represent the very core of our initiative.