Book excerpt: This book presents new research and theory at the regional scale showing the forms metropolitan regions might take to achieve sustainability. At the city scale the book presents case studies based on the latest research and practice from Europe, Asia and North America, showing how both planning and flagship design can propel cities into world class status, and also improve sustainability. The contributors explore the tension between polycentric and potentially sustainable development, and urban fragmentation in a physical context, but also in a wider cultural, social and economic context.