The coolest art museum in San Francisco?

If you've lived in San Francisco for any stretch of time (or haven't, but are SUPER into Berlin-style Ping-Pong), there's a small chance you've heard about The Secret Alley, which 1) isn't an alley, and 2) isn't exactly secret (the thing has its own Wiki).

I've been taking photos for as long as I can remember, and have been a bender of rules for even longer.

It's hard to believe in San Francisco, where community gardens are being replaced with condos, that an abandoned train yard could even still exist.