Mobtown Ballroom provides dancing to the public nearly every day of the week. They offer extended weekly lessons. But most importantly every Monday and Friday they offer a drop-in beginner lesson at 8 p.m. for $5 that you don't even need a partner for, and that you don't even need ANY prior dance experience for. They start from step 1 and the best part is there'll be 20 other people in the room all starting from the same place.
The evening just begins there. For more experienced dancers, and for people who want to (and should) stick around for dancing after the lesson, there is a DJ'd dance party from 9 p.m. until no one is standing anymore (usually around 1230 or 1).
Mobtown Ballroom is the greatest thing about Baltimore. It's fun. They put on a GREAT selection of live music. The people who go there are just the nicest human beings on the planet, and so are the owners.
If you're in Baltimore for a weekend, or even a couple days, try to make it down to the Ballroom. Your soul will thank you.
(check out their website for a calendar of events. It's updated SUPER regularly)