Heading south from St. Augustine  on State Road A1A at the tip of Anastasia Island is Fort Matanzas National Monument (8635 State Rd. A1A S., 904/471-0116, www.nps.gov/foma , 9 a.m.–5:30 p.m. daily, free). Overlooking Matanzas Inlet, the fort was constructed by the Spanish in 1740 to protect the southernmost water access to St. Augustine and was built at the site of two horrific massacres (matanzas is Spanish for “massacre”); in 1565 Spanish general Pedro Menéndez de Avilés slaughtered more than 200 Frenchmen who had surrendered to his forces.
The fort itself is located across the inlet on Rattlesnake Island, but a complimentary ferry leaves from the visitors center every hour on the half hour. Guided tours and small exhibits tell the story of the fort as well as the bloody history of the area.