City Lit does theatrical adaptations of great works of literature. They're known for their frequently produced adaptations of the famous "Jeeves" stories by P.G. Wodehouse; they also have chosen other pieces that focus on language, including Restoration Comedies.
The space is located on the second floor of a church, down the hall from the main stairwell. It's a good sized space designed as a thrust, and is intimate enough that there aren't really any bad seats. When walking there from the Bryn Mawr Red Line stop, there's (naturally) a Starbucks on the way and a great restaurant, Mia Francesca's, is right across the street.