I thought the original muscle beach is in Santa Monica right next to Venice......at least that's what the signs said when I was staying a hotel right next to it.
It has rings, chinup bars, dip stands and lots of ropes to climb. People have special gloves for hanging on the rings and do some insane tricks.
They moved the "original" muscle beach gym and all of that stuff, down the beach a little.
The place is still there though. You can get a membership for 120 bucks a year last I checked. You'll be working out outside with rusted plates, but if it's your thing, go for it.
It's there.
As far as the Gold's Gym in Venice... Pros still train there if they are around, but really, the world is different than it used to be.
Really great gyms are all over the place now, so people don't make the "pilgrimage" to Venice anymore.