Our Pick
Posted on @rawstates
K-25, the mile-long uranium plant
1945
Oak Ridge, Tennessee
Public domain · Wikimedia Commons
A mile-long U-shaped building, the largest roofed structure on earth when it was finished, built to separate uranium isotopes by pushing gas through acres of barrier material nobody had manufactured before. It ran on a scale of electricity that required its own power plants.
That was 1 of the hidden places.
Location: historic site
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