There is not a whole lot left along the Old Ridge Route that crawls through the Angeles National Forest north of Los Angeles, California. There are some remains of structures and a few historical placards. The road is no longer maintained and has fallen into dire disrepair, but, it is interesting. The road is gated about 5-10 miles south of Hwy 138 and probably gated somewhere before the north gate if entering the road from the Los Angeles area. So, you will have to turn around and retrace your steps.
Old Ridge Route, Angeles National Forest, California 2012