Walk Score, Arlington is the most walkable city in Virginia, barely beating out Alexandria. Clarendon is one of the most walkable sections of Arlington, getting about an 90 out of 100 score. This is no surprise to the residents here, as those who either live in the apartment high rises or flanking single family homes are within an easy walk to dozens of restaurants and bars, a Whole Foods, many high end stores, two Starbucks' and one anti-Starbucks.
Crystal City also ranked well this pedestrian-friendly competition, as our blue line cousin got very high marks. Thanks to Under One Roof for the tip, check out their blog post for more details.