When I visited New York in the mid-sixties, I went to Slug's pretty often. Great place to hang and listen to incredible music.
I heard Jackie McLean, Cecil Taylor, Sun Ra (on Monday evenings the first time around, then a full week the second time around)perform there. Also heard Charles Lloyd - did not care much for him - with a quartet that had Herbie Hancock, Henry Grimes, Pete LaRoca
The neighborhood was very colorful but pretty safe around then. I know this did not last very long!