It's Costa Mesa. Corner of 17th and Placentia.
Most of the "old school" punks I knew told me tales of the legendary fights between the punks at the Cuckoos Nest, the drunk cowboys from Zubies next door, and the OC cops.
I was just a baby when the club closed down. By the time I was "old enough" to go to shows, I would hang out at the showcase theater in Corona quite a bit. I probably saw over a hundred bands play there in the mid 90's. Just before they closed up one of the coolest all age venues ever, I got to see the Subhumans play there in '08.

