UPDATE: I recently removed the directions to this spot. Like usual, people are going out here and disrespecting it, pissing off residents, getting injured, littering, etc. BUT, after being given the suggestion to have a fee for directions to help weed out the disrespectful folks, I am going to do just that. If you are interested in giving a donation in trade for directions here or to other spots whose directions I've removed please go to this page for more details.
Personal Experience: First off, they don't call it Hellhole Canyon for nothing. This place is hot (I don't recommend going in the summer) it's filled with ticks, brush which rattlesnakes like to hide in, poison oak and the hike is rather bland. Don't go unless you're really interested in finding these homes because the hike is not that fun! And please come prepared with a lot of water, food (in case you get lost) and all other proper safety gear for hikes that can go bad. With that said, this literally appears to be an abandoned commune. There are children's rooms with drawings on the walls, kitchens with pots, pans and canned food, letters, a well, work station and SO much more! I am dying to know the history of this area but after speaking to the people who run the Hellhole Canyon website and the Valley Center historians, nobody seems to know!
Mission Basilica San
Diego de Alcala
Ocean Beach Farmers Market
Rum Runners Cave
El Campo Cemetary
La Casa de Machado y Stewart Museum
Old Adobe Chapel
Victorian Village Heritage Park
Kate O Sessions Park
Old Point Loma Lighthouse
Barry Koral's Fruit Farm & Museum