I worked at a local machine shop owned by a friends dad. It used to be a supper club and bar. It was called The Oaks and was popular during prohibition. Supposedly gangsters from Chicago and such used to stop by there as Winona, MN was a hotspot during that time period as it sits between the Cities and Chicago on the Mississippi.
What's interesting about it is that they made illegal alcohol there and in no small amount. One day my buddy showed me "the caves" which comprised of a bunch of tunnels underneath the whole building. They kept barrels down there and to this day (or at least 10 years ago) there were remnants of some metal from the barrels.
It is fascinating. From what I understand the tunnels led to homes around the Minnesota City area in case the police showed up they could book it. My buddy and I wore waders and tried to explore some of the submerged tunnels. Water pretty much filled them all and these tunnels were not straight. It felt like being in a pyramid or tomb. The tunnels would go up and down. Sadly, there was too much water to continue down one of the tunnels. The water went to our chests and turned to the left fully submerged. I always said it would be cool to get a suit and equipment then explore. Maybe find a skeleton or some crazy shit. It was a great experience.
Upstairs of the building still contained a small kitchen and about 6 rooms all painted bright colors. Some still have mattress springs left in there. From what I gather they had prostitutes there and those were the remnants. I don't know what else you would need odd colored rooms with twin beds for. I don't know how accurate everything I've been told is but the tunnels were pretty questionable and looked like they were made for sketchy stuff.
If he sees this somehow then he can tell the story that his dad always makes fun of me about. Maybe I'll tag him if this gets high enough.
Anyway, here's a link http://www.winonadailynews.com/news/local/winona-during-prohibition-was-a-hot-spot-with-gangsters-and/article_b0f56ef8-2f1e-11df-ad9d-001cc4c03286.html
There seems to be only a couple photos that have been digitized. That place much have been incredibly popular. Here's some photo's with what it looks like now and then. http://imgur.com/a/tffKA