Living in cities is gaining in attraction – a trend that is manifesting itself worldwide. In contrast to the booming industrial metropolises of the 19th century, with their slums and pollution, modern de-industrialization offers a dynamic for urban development. Areas that until recently were occupied by service arteries and infrastructure have become disused. Many old port facilities and railway yards are no longer needed for their original purposes, thus freeing city-centre sites for redevelopment. In addition, the ills of unrestricted mass mobility need to be redressed. Schemes to sink motorways beneath ground level or to lay them in tunnels are certainly expensive, but they mark an inestimable gain for a city and the landscape, even if critics argue that such measures merely hide the real problems.