Our Pick
Posted on @rawstates
Castillo de San Marcos
1695
St. Augustine, Florida
Schwerdf · CC BY 4.0 · Wikimedia Commons
Built of coquina, a soft shell limestone that absorbed cannonballs rather than shattering, which is why the fort was never taken by force in two English sieges. It is the oldest masonry fort in the continental United States and later held Geronimo's Apache prisoners.
That was 1 of the hidden places.
Location: documented spot
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