Test-Tube City: Five years after Katrina, New Orleans’ Lower Ninth Ward is largely uninhabited. The roads are filled with craters, 12-foot-tall grasses obscure stop signs and intersections, and you have to drive to St. Bernard Parish to buy groceries. But there’s still plenty of activity: The area has become a hub for architectural students and philanthropists, who see the Lower Nine as a blank canvas for building a 21st century city. Brad Pitt and his organization, Make it Right, have pledged to build 150 ultra-sustainable houses just like these two (Photo: Tim Murphy).