Throughout history, cities have been at the heart of human development and technological advancements. Although an element of planning can be discerned even in the earliest cities they have often evolved in response to the changing needs and aspirations of their inhabitants. Some cities have survived for millennia, including Rome, Athens, Cairo, Alexandra, Baghdad and Beijing, and are still flourishing. Other, once mighty, cities have disappeared, their ruins being unearthed by present-day archaeologists. Nowadays, massive growth is threatening the sustainability of cities and the quality of city life. Mass urbanization can lead to social instability, undermining the capacity of cities to be environmentally sustainable and economically successful. This book describes the exciting innovations already being introduced in cities as well as those which could become reality in the near future.