The Muros de San Juan are historic walls located in San Juan, the capital of Puerto Rico. Constructed in the 16th century, these fortifications were built to protect the city from invasions by sea. The walls are part of the larger San Juan National Historic Site, which includes several other fortifications. The walls stretch for about 2.5 miles and are made of stone and mortar. Visitors can walk along the top of the walls, enjoying panoramic views of the city and the ocean. The Muros de San Juan are a UNESCO World Heritage Site, reflecting their cultural and historical significance.