The LGBT center Cassero hosts various parties on some Saturdays and occasionally on other days (see the calendar at the Cassero website).
Worth a visit if only for the beautiful space in the large basement vault.
Usually not busy before 01:00, but then often with a long queue to get in.
The Cassero requires the Arcigay membership card which can be acquired at the entrance.

@ Via Don Giovanni Minzoni 18
Bologna 40121