ABSTRACT
Like trees, cities have root systems. The root system of a city has several elements. There are its networked infrastructures, the road tunnel and metro systems, water and energy utilities, metro lines, and cable and telephone networks which sustain the tiniest details of the lives of virtually all city dwellers. Then there are the sunken spaces gouged out of earth and rock: the hidden car-parks, the underground shopping spaces, the old mining tunnels, the secret military installations, the air raid or nuclear shelters. Finally, there are the built foundations, the root systems of buildings whose depth and complexity may even approach that of their more familiar surface parts.
