Spanish fortifications were military structures built by the Spanish Empire to protect their territories from invasions and attacks. These forts were strategically located along coastlines and borders, often featuring thick walls, towers, and moats. Notable examples include Castillo de San Marcos in St. Augustine, Florida and Fort San Felipe del Morro in San Juan, Puerto Rico. The design of these fortifications was influenced by European military architecture, incorporating elements like bastions and gun emplacements. They played a crucial role in the defense of Spanish colonies in the Americas and helped secure trade routes during the age of exploration.