What is the oldest existing fort in the United States?

The Spanish may have landed in St. Augustine in 1565, but it took them 100 years before they started building a fort that could adequately protect them from invaders. From 1672 to 1756, they constructed the oldest fort in the United States still standing, Castillo de San Marcos.

Asked by Jennifer Sinclair · Last updated 5 years ago · 5.6K views · SOURCE