The Common Ground Festival is actually held elsewhere in the city Westminster, Maryland: the grounds of the Carroll County Farm Museum. (A mile or so southeast of Western Maryland College). Westminster is about 25 or 30 miles Northwest of Baltimore.
It's a wonderful small festival with lots of very good traditional music,as well as other music and art. It's not very crowded. And since it comes at the end of week-long series of classes, many of the performers start accompanying each other (and some of the students, too), You'll hear combinations of performers you've never dreamed of before. One of the people who teaches a class in massage during the week-long session sets up a massage table near the main stage at the festival, and you can have body work done while you listen to great live music.
While the week-long classes may fill up, one can purchase tickets to the weekend festival at anytime--or at the gate!