4. Washington, D.C.
The city can be tough on drivers, but D.C. residents in Dupont Circle, Logan Circle, Downtown, Foggy Bottom, Mount Vernon Square, Columbia Heights or the U Street Corridor have their entire world within walking distance. Thank the Metro's buses and subways, which take 410 million riders off the road a year. Also thank the city's designers, who made it easy for ensuing generations to cluster amenities around that system's stops by making the city's center the focus of all its transit needs.