Castillo San Cristóbal, San Juan National Historic Site

Covering twenty-seven acres and with five outworks, Castillo San Cristóbal is the largest fortress ever built by the Spanish in the Americas. Construction began in 1634, the same year as construction on a wall around the city of San Juan. At the time, San Juan was not spread out over the entire island as it is today. It was just a small settlement on the western end, what is today the historic district called Old San Juan. The wall and fort were a response to an attack a decade earlier by the Dutch. Though unable to capture the existing fort of Castillo San Felipe de Morro and thus wrestle control of the island from the Spanish, the Dutch did burn the entire city before leaving the island.

San Cristóbal is located on the eastern end of Old San Juan and was built to defend the town against a land attack from the east. The island’s central and western Atlantic shoreline is rimmed by cliffs, so there was no way for an enemy army to land here. Much of the eastern end, however, is at sea level—this is where the few beaches on San Juan Island are located. While it might seem prudent to protect the entire island, there simply weren’t enough people in the 1500s and 1600s to do so. The Spanish did have a few small batteries on the eastern end by the late 1700s, but the entire population of the city was contained within Old San Juan, so this is where the major fortresses were built.

View to the east from Castillo San Cristóbal, San Juan National Historic Site

The original San Cristóbal was very small, and its construction was shoddy at best. Within two years, reports were already being sent back to Spain describing the deterioration. However, it wasn’t until 1765 that plans were made for a complete overhaul and modernization of all the forts in San Juan. The work on San Cristóbal took place between 1766 and 1785, and this is the fort that stands today. It was also during this time that all of its five outworks were built on the grounds.

Forts and Batteries of Castillo San Cristóbal

Fortunately, it did not matter much that it took 150 years for the fortress to be completed because the next major attack on the city after the 1625 Dutch attack didn’t come until 1797 during the Anglo-Spanish War in a week-long battle with the British known as the Battle of San Juan. While San Cristóbal did come under attack, most of the battle took place on the eastern end of the island, mainly between the British navy and Fortín de San Gerónimo de Boquerón and Fortín San Antonio. San Gerónimo still stands today, though it is not open to the public. It is best viewed at the Caribe Hilton Hotel. San Antonio was torn down in 1894 to make way for a new bridge.

Fortín de San Gerónimo at the eastern end of San Juan Island in Puerto Rico

Only the main fort at Castillo San Cristóbal is open to visitors. The surrounding grounds and batteries have been closed since 2019 for “renovation.” A Ranger told me that she didn’t know when, or even if, the grounds would open again. While you can no longer get onto the grounds to explore these structures, you can get great views of everything, including Old San Juan, from the upper levels of San Cristóbal.

View of the fortress grounds from the top of Castillo San Cristóbal, San Juan National Historic Site

Castillo San Cristóbal is open to visitors daily from 9 AM to 5 PM, except when closed on Thanksgiving, Christmas, and New Year’s Day. There is a fee to enter, and this is paid at the ticket desk inside the entrance to the fort (no cash). Tickets are valid for 24 hours, and if you previously visited Castillo San Felipe del Morro and got a ticket there within this time frame, it is good for entrance into San Cristóbal as well (be sure to keep your ticket). Various National Park passes are also valid. See the National Park Service’s Fees and Passes web page for the current prices.

Entrance ramp into Castillo San Cristóbal, San Juan National Historic Site

The main fort has four levels to explore. See the following web pages here on National Park Planner for photos and details of each level.

Dungeon

Plaza de Armas (main plaza)

Main Terreplein (main firing battery)

Cavalier (tallest structure in the fort)

There are two other structures open to visitors. One is the Fuerte del Espigón (Fort of the Point, aka Devil’s Sentry Box). This sentry box is part of the original 1634 fort. It was restored by the United States Army in 1938-39 and by the National Park Service in 2005. When on the terreplein of Castillo San Cristóbal, you can see it far down below. Visiting it, however, does require a short hike through extremely overgrown terrain—at least when I visited; perhaps Rangers might have weed-whacked the trail by the time you visit. See the Hike to Devil’s Sentry Box here on National Park Planner for details on how to get to it. If you are a photographer or just want some great photos, this is the place to be.

View of the Devil’s Sentry Box from the terreplein of Castillo San Cristóbal, San Juan National Historic Site

The second structure is the Joint Operations Center that was built by the United States Army during World War II. It is located in the dry moat between the fort wall and the San Carlos Ravelin. Today it houses an exhibit area, souvenir store, and restroom. There is also an abandoned National Park Service desk, and a door leads outside to a parking lot that is now gated, so I am guessing that this was once the main entrance and visitor center for San Cristóbal. The only way into the fort now is through the National Park Service visitor entrance on the Plaza de Armas.

Modern Joint Operations Center at Castillo San Cristóbal, San Juan National Historic Site

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