The facts speak for themselves: more than half the global population now live in urban areas. According to forecasts, three-quarters of the global population, i.e. around 7 billion people, will be living in cities by 2050. Alongside globalisation, urbanisation is indisputably one of the main trends of our time. Everywhere, discussions are addressing pressing questions on how to supply urban residents with housing, water, energy, education, health care and income opportunities. The key issues at stake across the globe include the economic, ecological and social development of a rapidly growing population and thus also political participation, governability, security and maintenance of stability.