Old San Juan (Spanish: Viejo San Juan) is the oldest settlement within the territory of the United States and it is the historic colonial section of San Juan, Puerto Rico.
Old San Juan is located on a small island connected to the mainland of Puerto Rico by bridges and a causeway.
The city is characterized by its narrow cobblestone streets and colorful buildings which date back to the 16th and 17th century when Puerto Rico was a Spanish possession.
The district is also characterized by numerous public plazas and churches including the Cathedral of San Juan Bautista, which contains the tomb of the Spanish explorer Juan Ponce de León. It also houses the most ancient Catholic school for Elementary education in Puerto Rico, the Colegio de Párvulos, built in 1865. With its abundance of shops, historic places, museums, open air cafés, restaurants, gracious homes, tree-shaded “plazas”, and its old beauty and architectonical peculiarity, “Old San Juan” is a main spot for local and internal tourism. A free Tourist trolley serves the city.
The oldest parts of the district of Old San Juan remain partly enclosed by massive walls. Several defensive structures and notable forts, such as the emblematic Fort San Felipe del Morro, Fort San Cristóbal, and El Palacio de Santa Catalina, also known as La Fortaleza, acted as the primary defenses of the settlement which was subjected to numerous attacks. La Fortaleza continues to serve also as the executive mansion for the Governor of Puerto Rico.
Many of the historic fortifications are part of San Juan National Historic Site.
Old San Juan along with La Fortaleza were declared a world heritage site by UNESCO in 1983.