So, last fall I got to go through an old waste water treatment plant; it’s been offline for decades but the building itself is still used for other stuff. This is the tunnel that serviced all of the piping.
Make note of the door at the upper right hand corner; it reappears later on. It’s at the far end of the tunnel, well away from the entrance/building basement.
This looking towards and very near the tunnel entrance from the building’s basement:
And here’s outside, topside, behind the building. Everything’s fenced off so idiots don’t drown in muck/get tetanus from old metal crap:
Remember that door? Here it is from the other side:
That’s all that I could salvage from my camera, about half the shots. Time for a new camera, I think – it gave me about 7 or 8 years of decent use.