Resumen
This paper takes a historical perspective on how cities have become less sustainable in terms of transport, but it will argue that many positive changes have taken place even before the current concerns over CO2 and oil. There seem to be many more opportunities for further change through the encouragement of high-quality city-based lifestyles that do not require high levels of carbon-based mobility. But it is in the newly emerging ?megacities? that the main problems occur, as there is a discontinuity between the slow growing, stable, and well-structured cities of the west and the rapidly growing, unstable, and unstructured cities of the east.