Located in a basement near the high-end Goethestrasse street, Jazzkeller is as unpretentious as can be in stark contrast. This spot has a rustic ambience and though small, they even have a grand piano.
This basement bar/pub has been all about the music since 1952 and has played its part in the history of jazz and will continue doing so in the future. There is a detailed history on the website and also handed out in English and German before the concert. There are live concerts on Thursdays, Saturdays and Sundays. Wednesdays witness new and old artists come together for a jam session. Friday nights are DJ nights and the pub is converted to a small club where people can raise the roof till 03:00. The concerts are given by bands visiting from all over the world.
Last weekend a band from New York played there and I watched its members greet some of the regular audience members as if they were old friends and mingle with the crowd over drinks during the break! It was like attending a house party with a private concert!
Word of advice: Only go there, if you want to enjoy a night of music with a couple of drinks, not if you want to catch up with a friend, the regulars will not appreciate that!