The friendliest blues bar in Chicago is a joyous melting pot of cultures. It's owned by an Italian, in a Latino neighborhood, clientele is black and white, so are the musicians. The best of local talent plays here, in an intimate space, which gives back to the blues community with birthday parties for elder statesmen and a yearly sequence of classes about various blues-related topics.
As a youngster in Italy, Tony Mangiullo collected blues '45s, and dreamt of being in a blues band. Eventually, with his mother ("Mama Rosa"), he moved to Chicago and set up shop. Occasionally, Tony breaks out the drum sticks, gives the bands' drummer a night off, and sits in with the band. Rosa's is, in my opinion, the best place to see blues in Chicago, at least if you've the opportunity. Artists are mostly local (and good!), including Grammy-award winner Sugar Blue and guitarist Melvin Taylor. There's also a pool table, and lots of interesting graffiti and photographs on the walls.