Castillo de San Marcos

Castillo de San Marcos is a historic fortress located in St. Augustine, Florida. Built by the Spanish in the late 1600s, it is the oldest masonry fort in the continental United States. Made from coquina shells, its thick walls were designed to defend against pirates, pirates, and enemy nations. Over centuries, it changed hands several times before becoming a National Monument. Today, it serves as a museum, offering visitors insights into early Spanish-American history, colonial defense strategies, and the region’s cultural heritage, all within a well-preserved, impressive stone structure that highlights early American military architecture.