I train at Baltimore bjj and I will try to be as unbiased as possible.
First, are you in Baltimore proper? People say they are moving to Baltimore and are in Cockeysville, Towson, Parkville, etc....
There are quite a few schools depending where you are. If you are in the actual city, My gym, Ground Control(the main one), Conquest and Gracie jj Baltimore are anywhere from 5-20 minutes away. Crazy 88's main academy is in Elkridge, which is about 25-30 minutes depending on traffic.
Baltimore BJJ is a great place to train. Lots of different belt colors, two mat areas, a rock wall(seriously) and other fun things. Hard training with a bunch of awesome people. Team Balance affiliate
Ground Control is run by John Rallo. He had a big hand in legalizing MMA in Maryland and is a Renzo Gracie black belt. Another good group of guys, though the main school isn't know for competing as much as the affiliate schools(Owings Mills, Harford county and Columbia). I know the Columbia school is run by an Alliance black belt, Joao Paulo.
Conquest is run by two Vicente Jr black belts, Lance and Kail. Nice space, solid competitors and a good group of dudes(running theme in the area). In Millersville, so again, depending on where you are, it could be a quick trip.
The Gracie school is run by a purple belt who used to train with us and is right by Orioles stadium. They do the Gracie stuff and regular training. Nick is a good guy and I believe a Judo brown belt.
Crazy 88 is a Team Lloyd Irvin affiliate. I'm not going to go into the whole scandal ordeal, that is for you to decide. Run by black belt Julius Park and has a bunch of studs there like Tim Spriggs and Tye Ryan. Solid school.Haven't had personal interactions with the guys there, so I can't comment on how they are as people(good or bad).
Those are the main ones that are popping out to me at the moment that I have info on but there are a bunch more. I suggest trying every place and see how you like them. Feel free to PM me with any questions. Have fun with your search.
