My favorite is not very accessible. (It is possible to get a tour, but it isn't as easy as driving up and entering.) It is the Big Sur Lighthouse Station on California's Big Sur Coast, sort of in my extended photographic backyard.
The lighthouse station is (or at least was) so isolated that for the first years of its existence the only realistic way to get there was on the monthly resupply ship. It sits on a mountain barely connected to the mainland by a sandy strip, and it extends well out into the ocean.
Continuing with my Point Sur Lighthouse Station theme, here is another one from a slightly different angle that includes a bit of the coastline leading toward Sur Point.
digital photo)
