What was the concrete used by the Spanish to build the first fort in the United States?
Answer Coquina
The Spanish discovered a new type of limestone which they called coquina. Unlike other types of limestone, coquina was lighter and more porous. This did not seem to make it a great choice for a fort; however, the Spanish had no alternative. It turned out the coquina was perfect as the air pockets made it absorb canon and gun fire instead of it shattering. There are still canon balls burrowed in the walls of Castillo de San Marcos.
Asked by Jennifer Sinclair · Last updated 5 years ago · 5.7K views · SOURCE
