Christopher Alexander, a British-American scholar, differentiated an old (natural) city from a new (planned) one by structure. The former resembles a “semilattice”, or a complex system encompassing many interconnected sub-systems. The latter is shaped in a graph-theoretical “tree”, which lacks the structural complexity as its sub-systems are compartmentalized into a single hierarchy. This structural distinction explains why, or...

The characteristic feature of a contemporary city is its inconvenience and oppressiveness caused by the hitherto dominant paradigm of urban planning based on car mobility. As a result, the inhabitants have to cope with air pollution, noise, spatial barriers, sedentary lifestyle and other factors which worsen their health and quality of life. Ecological and physically activating urban mobility thus plays an increasingly important...