Back in good old 2007 you could party here 22 hours a day on Sundays! Twice in recent years voted THE NUMBER ONE CLUB ON EARTH by the readers & DJ's of DJ Magazine!
As everyone else says, best zoo around. But more than that, the surrounding museums and Balboa Park are awesome too. I suggest getting a re-entry stamp and go back and forth as much as you like.
This is a must for zoo fans. Don't skimp on time for your visit; there's a lot to see here. Better yet, plan several days so you can check out the zoo's sister properties.