City planning is the key-stone to tackle the question of climate-change and to involve adequate action. In Part I of this book, the theory of space-economy is presented. Opening up a new conceptual and operational toolbox for policy makers, practitioners and scholars, the theory of space-economy is based on a rigorously structured thinking and acting in the field of sustainable urban planning and architecture. Europe has the greatest experience in sustainable city planning worldwide. In Part II, four of the most remarkable experiences (Vauban in Freiburg i.B., Kronsberg in Hannover, Western Harbour in Malmo, Hammarby Sjostad in Stockholm) are presented, dissected conceptually and operationally a radically new way. The interest of the approach is not limited to European countries. In Part III is developed a project in Asia, in Ho Chi Minh City, faced with dramatic threats due to climate change and rapidly growing tidal and sea-level rise. Based on the experiences presented in Part II, the approach is integrated in this completely different context, thus becoming fully effective at a much bigger scale.