City Sports Store (Washington, D.C.)
City Sports is a shining example of just how good outdoor fun can be in a metropolis. City Sports runs the free-services gamut with gait analysis for runners and racquet stringing for tennis players, and the sporting goods store stays stocked up on almost every type of gear for any sport that you could want to play or any workout you want to do. You'll find Crossfit-specific shoes, ultimate Frisbee gear, triathlon apparel, volleyball, squash, boxing, golf, lacrosse, and swimming necessities. Chances are, if you want to find it, City Sports will have it.
More info: citysports.com