A Brookings Institution survey ranks the 30 biggest metropolitan areas according to the number of "walkable urban places" relative to the area's population. The WDC area is ranked as #1.
As one who, over the years, has embarked photo walks I could not agree more.
Click photo to view my Pedestrian 2007 and ongoing pedestrians project.
One of the reasons that I have always enjoyed WDC and NYC is due to their walkability.