Where to search for basement/underground real estate?
Wasn't sure where to ask this question, so I hope it's ok here. My friends and I had an idea that would require a space that is below the ground floor of a building (with preferably an alleyway entrance). But none of us have searched for commercial real estate before. Where do we begin? 
[{"id": "cq9pbm4", "text": "This sounds really shady...\n\nOk. I'll bite. Meth lab?", "replies": [{"id": "cq9ui4g", "text": "More along the lines of secret clubhouse/lounge. We realized that we're finally all making enough money that, if we split the cost, we can afford to lease a place.", "replies": [], "depth": 2}], "depth": 1}, {"id": "cq9r27e", "text": "call a broker.  call a broker.  call a broker.  ", "replies": [{"id": "cq9uilq", "text": "Any recommendations on how to find a good one?", "replies": [{"id": "cq9uq3b", "text": "Sure.  Where area are you in?  Depending on the area I may have a name or two.  But other than that-  since you are a potential tenant, you may want to find someone that is a core network member.  Other than that I've generally found ccim and or sior certified agents are good.  ", "replies": [], "depth": 3}], "depth": 2}], "depth": 1}, {"id": "cq9urcx", "text": "Post what city, you never know who is watching.  And for a basement space be prepared for a lot of cash put into architectural fees, build out, fire compliance etc.  Cities hate basement spaces", "replies": [], "depth": 1}, {"id": "cq9ww65", "text": "loopnet", "replies": [], "depth": 1}, {"id": "cqa6k0k", "text": "Many buildings in major cities have lower level space that is just empty and they will lease for cheap. The problem is most are also not going to be cool with people just hanging out / drinking down there. From a landlord's perspective the risk of other tenants complaining / legal insurance issues are going to be more than your rent is probably worth. Would you want to get a liquor license?", "replies": [], "depth": 1}]