Red Gate Woods: The final resting place of the world's first nuclear reactor
atlasobscura.com
atlasobscura.com
Which makes you wonder who else will sabotage it in the years to come. Maybe the word "danger" is next to go?
https://en.wikipedia.org/wiki/Natural_nuclear_fission_reacto...
https://medium.com/the-physics-arxiv-blog/in-the-1970s-scien...
The relevant part was the waste processing area, which had a smokestack (presumably for power). Painted eighty or a hundred feet up was a large stripe. The guide said that that was how deep they were going to bury the building once it had reached end of life.
Having just watched "Beneath the Planet of the Apes" I could imagine a future where explorers go down the stack because they were attracted by the 50+ feet that would remain above ground. Curiosity is hard to fight.
I agree with you, our successors will question why there's a tunnel in the ground, why a painted stripe appears within the tunnel, and for what purpose the tunnel was hidden.
Though I'm incredibly pessimistic about our future, no matter what signs and warning we give, human curiosity wants to know for what substance those warnings are there to dispel people from, and human greed will ironically want to claim it all.
I am thankful that I got to see the depths of major hydro-electric facilities in my home state as a child. They inspired awe and wonder in our ability to engineer massive things; though such words were not at all within my vocabulary at that age.
The marker is probably from 2000, when large rocks were placed over the entire site. It already looks dated.
[1] https://upload.wikimedia.org/wikipedia/commons/9/96/SL-1Buri...
Plot M is about half a mile away from Site A, and is easily missed. If you look on Google Maps for a small clearing just northeast of Site A, that is where Plot M is. (41.707279, -87.910550)
The Forest Preserves of Cook County website has some good information about the history of the site: http://fpdcc.com/site-a/
Link for the curious: http://manhattanprojectbreactor.hanford.gov/
Also, the trails around that part of the FPDCC system are amazing. They might be the one thing I miss about suburban life.