The New York Times has a really interesting story about Arcosanti, an experimental Arizona "town" that was begun in 1970 with the hopes of creating a new kind of city. From the Times :
At first approach, the skyline -- a pair of concrete apses, a network of modular concrete dwellings, a rusty old crane -- fails to make much of an impact. But it swells with the dream behind it. The Italian architect Paolo Soleri, a former student of Frank Lloyd Wright , began construction of this ecologically harmonious community in 1970.
With its radical conservation techniques and a brilliantly scrunched-together layout, Arcosanti was intended to reinvent not just the city, but also man's relationship to the planet: picture a 60s vision of a Mars colony, but with a cutting-edge, eco-friendly design. Evaporative cooling pools release moisture into the air. In winter, heat from the foundry furnace is collected by a hood and sent through the apartments above.
Though the architecture of Arcosanti looks awfully dated, the anti-sprawl goals of the place seem pretty au courant -- especially with Phoenix spreading like a monster 70 miles south.