There is more to globalisation than international financial and trade networks. Globalisation also creates an international urban society: the Cosmopolis. The aim of the Internationale Bauausstellung (International Building Exhibition) IBA Hamburg is to adapt the city to the needs of citizens of this cosmopolis and to give them the opportunity to develope. Volume 5 of the IBA’s series of publications deals with the structure of the communities inhabited by citizens of this cosmopolis — the places where they live, move and operate. In the light of demographic change, the book focuses on questions such as whether — and, above all, how — the armoury of urban planning and of architecture can be used to overcome the social and cultural barriers within urban societies, how ethnic and cultural diversity can become positive strengths, and how this can happen under the conditions of a worldwide trend of urbanisation that is coming up against its ecological limits.