Look around: the largest migration in human history is under way. For the first time ever, more people are living in cities than in rural areas. Between 2007 and 2050, the world’s cities will have absorbed 3.1 billion people. Urbanization is the mass movement that will change our world during the twenty-first century, and the “arrival city” is where it is taking place.
 
The arrival city exists on the outskirts of