Castillo de San Marcos National Monument

Overview

Castillo de San Marcos National Monument is a Certified Autism Center™ committed to providing a welcoming and accessible experience for all visitors, with staff trained to better assist autistic and sensory-sensitive guests. As the oldest masonry fort in the continental United States and the only surviving 17th-century military structure of its kind, the Castillo has stood watch over St. Augustine since 1695. Built from coquina, a unique shell-based stone found locally, the fort's walls were designed to absorb and deflect enemy fire, helping protect Spain's colonial settlement for centuries. Today, visitors can explore the historic fort, learn about its fascinating past, watch cannon demonstrations, and experience living history programs and reenactments throughout the 20.5-acre national park.