Our Pick
Posted on @rawstates
Cave of the Mounds, opened by a dynamite charge
1939
Blue Mounds, Wisconsin
Caves Rock · CC BY-SA 3.0 · Wikimedia Commons
On 4 August 1939 quarry workers set a charge in the south slope of the east Blue Mound and blew open a hole into a limestone cave nobody knew was there. The quarry stopped work that day and never restarted. What was under the rock was worth more than the rock. It was made a National Natural Landmark in 1987 and gets called the jewel box of American caves, mostly for the density of its formations.
That was 1 of the hidden places.
Location: historic site
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