Large urban centres are pre-eminently the places where humans create, exchange and meet one another. And yet cities are often held responsible for every social ill imaginable. François Ascher analyses here the tendency to concentrate people, activities and wealth in metropolises.

But is this a generalised trend? What specific forms does it take? Will the new means of communication put an end to this sort of concentration? Are those city dwellers who have the choice going to abandon the large urban centres — or will they continue to seek the greater variety and liveliness of metropolitan life? How can we master urban development? What sort of urbanism should we choose?

• A profound reflection on the evolution of the contemporary city and of the forces that drive it.

François Ascher is a professor at the French Institute for Urbanism. He is the author of La Société évolue, la politique aussi (2007) and Le Mangeur hypermoderne (2005).