Henry Charlton Beck refered to this place as the Pasedena Terra Cotta factory, but I have it on good authority that he its real name is the Brooksbrae Brick Factory. Whatever its actual name, the factory burned down in the early 1900’s, and lately has been tagged with the usual graffiti. If you visit you’ll find two underground tunnels, with one tunnel having two levels. The tunnels are cramped (I had to crawl on my hands and knees) and are nothing at all of interest. It’s just a short tunnel about 65 feet long. There are more pictures here.
Pasadena Terra Cotta