San Juan National Historic Site

San Juan National Historic Site is a complex of massive stone fortresses and thick defensive walls in the northern part of Old San Juan. The buildings and military structures spread across several blocks and form a large fortification system.

Spanish colonists began building the fortifications in the 16th century to protect the harbor from pirates and competing European navies. Construction of the complex continued through many generations as it was expanded and improved over time.

The fortifications show Spanish military architecture built over many centuries, and they still shape how Old San Juan looks today. Walking through the structures, you can see how different building styles and techniques were used by builders across different generations.

You can explore the fortresses on your own or join guided tours offered daily. Wear comfortable shoes, as the paths are paved and there are many stairs and transitions between different areas.

The site preserves around three-quarters of San Juan's original city walls, making it a rare example of a complete fortified urban core. This places it among only three remaining walled cities in North America that retain such substantial portions of their original defenses.

Location: Toa Baja

Operator: National Park Service

Phone: +17877296777

Website: https://nps.gov/saju

GPS coordinates: 18.46844,-66.12197

Latest update: December 7, 2025 20:49