The devastating effects of the attacks by the English in 1598 and the Dutch in 1625 forced the Spaniards to expand the fortification system of San Juan. They lengthened the city walls and constructed a sentry box or “garita” (Garita del Diablo) on the coast to the east of El Morro and also a small artillery platform on top of a hill named San Cristóbal.
Named after the saint patron of land travelers, Saint Christopher, Castillo San Cristóbal, is considered the largest fortress built in the Americas. It was built for the purpose of protecting the city of San Juan from attack by land from the east. It is a fortification with three levels and an extensive series of outer defenses and it took over 150 years to complete. The Irish born Tomás O’Daly was Chief Engineer and he was assisted by Juan Francisco Mestre.
Following the principles of the French-influenced “Vauban-style fortress” (featuring irregular and triangular shaped bastions) and a “Defense in Depth” strategy, San Cristóbal was built with a deep dry moat and a series of tunnels. These tunnels protected soldiers from enemy fire and allowed the safe movement of troops, weapons and supplies. This enabled the defenders to engage the enemy before they reached the city gate if attacked by land. Gunpowder could be placed in other tunnels, called “countermines” to explode beneath the feet of an attacking enemy. Countermining tunnels served to destroy parts of the battlefield and also had the potential to block enemy access to the fortress through them.
The main plaza of San Cristóbal was the heart of the fort. It is where troops drilled, were inspected and assembled for formal events. Eleven casemates border the plaza. Casemates are large vaulted, bombproof rooms designed with gun ports for cannon. The arch in the ceiling provided strength to support gun desks above and withstand the concussion of shells exploding overhead. Casemates also housed officers’ quarters, barracks, storage areas, the kitchen and latrine. Thick-walled gunpowder magazines were built close by the plaza, casemates and tunnels and were designed to provide optimal conditions for the storage of the powder. Artillery ramps provided access to the main firing battery and the dry moat.
The fort was designed to catch and retain as much rainwater as possible and the 5 cisterns underneath the plaza could hold approximately 800.000 gallons of rain water. These cisterns are in use today for the maintenance of the park and are an excellent example of how we can learn about the self-sufficient practices of centuries ago.
Among the most interesting features of the interior of San Cristóbal is the dungeon which shows original late 18th century drawings made by an unknown prisoner. It is here that a friar was chained to the wall for over 20 years for the crime of murder. There was no need for instruments of torture in this dungeon; the dark gloom, the rodents, insects, isolation and stifling heat of place itself provided sufficient punishment!
Visitors will appreciate some of the additions made by the US Army during World War II. There are two coastal observation posts and a 1942 bunker which serves as our current Visitors’ Center. The theater located in the visitor center shows a movie in English and Spanish about the history of the park.
Castillo de San Cristóbal is massive and imposing; a masterpiece of 18th century military engineering and innovation. Modern military strategists and history buffs enjoy learning of the ingeniousness of its design; all visitors are inspired by the beauty of the architecture and the setting.
Last updated: December 26, 2019