If you brought a mountain bike instead of a road bike, there is a great set of trails adjacent to the rec center.
The rec center enters off of Braddock Road, and while Braddock isn't great for bikes, crossing to the opposite street gets you into some good neighborhoods. The PPTC does regular rides starting there, but I don't know the route they take. Here's the only cue sheet they have starting there. http://www.bikepptc.org/node/3738
I ride that area fairly often. If I come up with a route for you, I'll post it.

edit - Just remembered another ride that starts in the neighborhood across from the center. http://www.bikepptc.org/node/3863
That one's a good loop with several good hills.

Just be aware that with the last two snowstorms dumping 45"+ on our area, many of the roads are narrowed by snow piles that will be around for several weeks. The refreezing every night means a lot of ice.