what are they? I thought maybe a watchtower of some kind, but I can see 2 at the bottom of the cliff, which would be pointless, and 2 storeys seems a lot of effort for something else.
Yep Cornish beam engine was a massive innovation back in the 1830s which put Cornwall on the map as the No1 tin mining area in the world. Those two engine houses you can see down at the bottom of the cliff would have looked like this back in the day please log in to view this image
Pretty sure you can get day excursions from SF to Muir national monument and yeah, car is a hinderance in the City Unless you want to recreate that scene with Steve McQueen chucking his Ford Mustang around the streets