The BCC Y on Old Georgetown Road is a great place to start.

Hi! I learned to play in my early twenties -- had never picked up a racket before -- and now I am a total junkie. Love it. I live in Virginia so now sure this will be helpful, but...

First, you may want to start with a series of private lessons.

I would look into the following:
- Rock Creek (in DC)
- Hains Point (in DC)
- I live in Falls Church City and they do have some daytime clinics, I think (falls church parks and rec)
- RJ Tennis (google it), but I think most of their facilities are in VA
- www.paulbresstennis.com, they actually do some stuff in MD I know.

You could find pros at any of these organizations to do private lessons.

We joined a pool that has beautiful tennis courts but lessons offered there are only in the after work hours and that doesn't work for me. Mo Co Recreation does not seem to offer tennis at least in the fall. Also, if you've learned tennis as an adult how did work out? I'm in decent shape thanks to regular gym workouts but have never been much of an athlete.