Our Pick
Posted on @rawstates
Soudan, the deepest mine turned laboratory
1882
Tower, Minnesota
The original uploader was AaronRoe at English Wikipedia. · CC BY 2.5 · Wikimedia Commons
Minnesota's first iron mine went half a mile straight down and closed in 1962. The rock above it is stable and old enough to screen out cosmic rays, so physicists moved in, a detector at the bottom of the shaft spent years catching neutrinos fired through the earth from a beam five hundred miles away in Illinois.
That was 1 of the hidden places.
Location: documented spot
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