Go on a sunday afternoon to see weekly (FREE) afro-cuban music.

yes the street gets packed with people so as you would anywhere, be careful with your belongings. people are generally friendly, and the music is a must for Havana. This is the epicentre of Cuban music. If you miss this off your trip, you don't know what you're missing!

Rumba!

I got a standing lapdance in the middle of the street by some girl, afterwards I bought her a cervesa or whatever it's called, it was totally worth it. Also there's a lot of music and people in the street so keep your wallet in your front pocket and keep alert