Our Pick
Posted on @rawstates
Thornton Quarry, a mile and a half of hole with an interstate across it
1928
Thornton, Illinois
Ken Lund · CC BY-SA 2.0 · Wikimedia Commons
This is one of the largest aggregate quarries in the world, about a mile and a half long, half a mile wide and 450 feet deep at its deepest. Interstate 80 and the Tri-State Tollway cross it on an earth dike driven through the middle. Gallagher Asphalt has worked the grounds since 1928. The rock is a Silurian reef laid down under a shallow sea, and part of the excavation now serves the Chicago Deep Tunnel project as a reservoir holding billions of gallons of stormwater.
That was 1 of the hidden places.
Location: historic site
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