UCLA steam tunnels map and entrance pic
Back in 1997 a couple of friends and I at UCLA stumbled on an entrance near Moore Hall to the steam tunnels under the university. We went down about half-a-dozen times and mapped them out, and even took a few other people on "tours". We weren't troublemakers, just explorers.
The first pic in that album is the map my friend made. In addition to the notes in the map, here are a few other interesting details.
We called the blue room east of Royce the "toilet graveyard". It looked like a natural ravine that had been roofed over with a street, and was the largest underground open area we discovered. It contained hundreds of discarded toilets and other debris.
From the tunnel access in Royce Hall we were able to get into the West tower. If I remember correctly, the stairs into the tower ascended from the third floor. I think we looked for access into the East tower but couldn't find our way up. While up in the West tower I remember thinking that it was a once-in-a-lifetime experience, and we lingered up there for a while.
The steam tunnels were lit and generally navigable. They weren't bright, but we didn't need flashlights; the insides of the buildings were darker. There were some tight spaces, but it nothing too bad. It was warm and humid, as you might expect. There were plenty of dangerous electrical and mechanical equipment, and we were careful not to touch anything. Someone got burned on a steam pipe, but I forget who (not me).
Finally, the second picture in the linked album is from a recent visit to UCLA. This is the door on Royce Hall that I believe we used as a main entrance. There were many exits, but this was the only unlocked entrance.