When I was in high school in Missouri in the mid 80s, there was an abandoned water treatment plant we used to go to for BB gun wars. It was a pretty cool place, I was always amused that the place wasn't really fenced, aside from a berm to block cars from driving in.
They finally tore the place down a few years ago, and a police shooting range is now on the site.
I found some photos of the place here:
EquaDome
Turns out the plant was built to supply water to a TNT plant a few miles away, which was later used for uranium processing in the Cold War.
Weldon Spring Ordnance Works - Wikipedia, the free encyclopedia
That place was abandoned at the time as well, but we never tried to get in there, as it had guards. Good thing, turns out it was an irradiated and toxic mess. Evidently they have since torn the whole place down, cleaned up what they could, and buried the rest under tons of gravel.