Most of the pictures you see of Salvation Mountain only show the front facade, but Knight has been working for years on a system of forest-like passageways on the south side.
Other lesser-known features of Salvation Mountain:
CLOCKWISE FROM TOP LEFT: art car, model of the Mountain, grotto, building materials (satellite dish and straw bales)
We meet an art student from the city who appears to be Leonard's intern, and a couple of Jesus freaks who are hanging out on top of the Mountain. From the summit, you can see Slab City.
Slab City from Salvation Mountain