San Juan National Historic Site

San Juan National Historic Site protects major Spanish colonial fortifications and the city walls that once defended Old San Juan in Puerto Rico. The site preserves two primary forts and the surrounding defensive structures that controlled access to San Juan Bay.

Prominent features include the ocean-front Citadel known as Castillo San Felipe del Morro (El Morro) and the larger, landward Castillo San Cristobal, along with the adjoining city walls and gates that wrap parts of Old San Juan. These masonry fortifications are architecturally and historically significant for their role in Caribbean colonial defense.

Spanish military engineers began building major fortifications in the 16th century and continuously adapted them through the 18th century as artillery and strategic needs changed. The site later came under U.S. administration and is managed to preserve its historic fabric and to interpret its role in colonial-era maritime defense.

The historic site sits in the heart of Old San Juan on the islet that forms the entrance to San Juan Bay, directly adjacent to the historic street grid, shops and waterfront promenades of central San Juan.

• Colonial fortifications: The site includes multiple Spanish colonial forts and city defenses that date from the 16th to 18th centuries and are key elements of Old San Juan's historic fabric.

What to See #

• Castillo San Felipe del Morro (El Morro): A large coastal fortification built and expanded by Spanish colonial authorities between the 16th and 18th centuries to guard the entrance to San Juan Bay.
• Castillo San Cristobal: An extensive 18th-century fortress designed to defend the eastern approaches to Old San Juan, featuring multiple bastions and tunnels.
• San Juan city walls and gates: The colonial-era city walls and gates that encircle parts of Old San Juan and were constructed over several centuries as a combined defensive system.