Difficult problems do not always require far-fetched solutions, but to arrive at the solution a change of perspective may be in order. The City as a System advocates such a change of perspective in the study of the urban environment. It posits that designers who wish to truly improve the functioning of the city and solve tricky urban problems should not only focus on the visible, spatial character of the city, but should also conduct research into its underlying system—into the operation, use and performance of the urban fabric.The authors view the metabolism of the city as that of a living organism and argue that the urban body—as the place where much of our resource use culminates—plays a crucial role in the transition toward a more sustainable living environment.