Map - Old San Juan (Viejo San Juan)

Old San Juan (Viejo San Juan) is a historic district located at the "northwest triangle" of the islet of San Juan. Its area roughly correlates to the Ballajá, Catedral, Marina, Mercado, San Cristóbal, and San Francisco sub-barrios (sub-districts) of barrio San Juan Antiguo in the municipality of San Juan, Puerto Rico. Old San Juan is the oldest settlement within Puerto Rico and the historic colonial district of the city of San Juan. This historic district is a National Historic Landmark District and is listed on the United States National Register of Historic Places as the Old San Juan Historic District. Several historical buildings and structures, particularly La Fortaleza, the city walls, and El Morro and San Cristóbal castles, have been inscribed in the UNESCO World Heritage Site list since 1983. Historically the mixed use commercial and residential real estate in the main streets like Cristo Street, Fortaleza Street (north) from Tanca Street to the Governor’s Mansion is the most valuable in the area and it has kept its value and increased steadily through several years despite the past economic turmoils.

Old San Juan is located on a small and narrow island which lies along the north coast, about 35 mi from the east end of Puerto Rico, and is united to the mainland of Puerto Rico by three bridges. It is bounded by the Atlantic Ocean to the north and to the south by San Juan Bay (or "Bahia de San Juan")—which lies between the city and the mainland. On a promontory (Spanish: morro) about 100 ft high, at the west end of the island and commanding the entrance to the harbor, rise the battlements of Fort San Felipe del Morro, in which there is a lighthouse.

The "Caño de San Antonio" lies to the southeast, where the island of Old San Juan connects to the mainland through Santurce, by three bridges, "Puente Dos Hermanos" (Ashford Avenue), "Puente G. Esteves" (Ponce de León Avenue) and "Puente San Antonio" (Fernández Juncos Avenue).

The city is characterized by its narrow, blue cobblestone streets, and flat-roofed brick and stone buildings, which date back to the 16th and 17th centuries—when Puerto Rico was a Spanish possession. Near Fort San Felipe del Morro, is the Casa Blanca, a palace built on land which belonged to the family of Ponce de León.