I've always had a fascination with the styles of eras past; vintage design, fashion, and art are always cool, but old architecture even more so catches my eye. Far too often in the U.S. we discard without appreciation, though fortunately some groups of our society recycle, remodel, or reuse these things in our environment to keep our footprint minimal. Not all live by that mentality, they just leave it, forget it, and make something new.
While cruising the California coastline I saw this unique building and had to see what it was. I hiked past the government signs deterring civilians away, stating the cliffs were extremely dangerous (somebody without hiking experience could very easily die here).
The building was bunker during WWII, and served as a lookout point before radar the norm.
Farther north, I kept with the military theme and visited the abandoned Naval base on Mare Island. The majority of the area is heavily blocked off, but this one building is the hotspot for trespassing.
And then there was this Dutch windmill, restored and appeared to be functional.