El Castillo de San Marcos

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This 400-year old Spanish structure is Saint Augustine’s most famous attraction. It was built by the Spanish colonizers over a 20-year period in the late 1600s to replace nine previous wooden fortifications. It effectively protected the colony’s strategic location and inhabitants from attacks by pirates and the British.

Today it is a National Monument run by the US National Parks Service (NPS). Occupying a 20 acre (8 ha) site, it is the oldest and best preserved masonry fort in the USA. Well, it’s not “masonry” in the usual sense, because it was built of coquina, a shell-rock that is soft and porous underground, but becomes hard when cut into blocks and exposed to air. Then it acts as a sort of structural shock-absorber, somewhat like tacky marshmallow, so that enemy cannon balls could only embed themselves in it without penetrating or exploding and splintering their target. The defenders, however, could counter with dozens of 6- and 18-pound cannons. This virtually impregnable tribute to Spanish military engineering was never captured. The use of coquina also lessened the amount of reconstruction the NPS had to do to prepare for its re-opening.

El Castillo has had a fascinating history, including sheltering the entire population of the colony during a 27-day siege in 1702 by British ships and troops, in which there were only two Spanish casualties. It has also flew six different flags over the centuries. There is far too much to tell in this article, so may I suggest http://www.exploresouthernhistory.com/castillodesanmarcos1.html

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