View of the fort plaza and Old San Juan from Castillo San Cristóbal’s cavalier, San Juan National Historic Site

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A cavalier is the tallest structure within a fort, often a tower of some sort that stands on its own. It serves as an elevated observation area and terreplein (artillery deck), typically supplementing the fort’s main terreplein on a lower level. When first built in the 1630s, the cavalier of Castillo San Cristóbal was a semi-circular tower surrounded by a north and south bastion that were connected by a curtain (wall between two bastions). While the fort was completely overhauled and expanded between 1766 and 1785, all of these features were incorporated into the design and still exist in some shape or form today.

The Spanish often gave names to buildings and other architectural features, and they called the cavalier of San Cristóbal Caballero de San Miguel (Cavalier of Saint Michael), naming the structure after the patron saint of those in the military and other dangerous professions (among other things). The Spanish name is typically shortened to El Caballero. National Park Service signage at the fort refers to it as the Observation Deck.

The cavalier of San Cristóbal is hard to miss. Once you enter the fort through the guardhouse that the National Park Service uses as its current ticket office, you will be staring directly at it. A steep ramp leads to the top.

Ramp to the top of the cavalier at Castillo San Cristóbal, San Juan National Historic Site

Today’s cavalier, which extends the full width of the fort, north to south, is much larger than when it was originally built. The southern end (right side) of the original structure ended where the current barracks begins (the barracks is the building that looks like an office building you might see in Old San Juan). Where the northern end was is not as clear, but I believe it extended just enough to encompass the right-hand tunnel at its base. Regardless, it did not extend as far north as it currently does. If you walk up to the top, look for the curved section of the eastern wall. That is the extent of the original cavalier.

Approximate boundaries of Castillo San Cristóbal’s original cavalier

Top view of Castillo San Cristóbal’s cavalier

Curved wall marks the footprint of the original 1630s cavalier of Castillo San Cristóbal, San Juan National Historic Site

Tunnels at the base of Castillo San Cristóbal’s cavalier, San Juan National Historic Site

Between 1766 and 1773, the top of the cavalier was raised six feet, so you really aren’t standing on the original when you are at the top. To extend the structure to the south, the Spanish could have simply built a tall wall with a terreplein on top, but instead they built a barracks and used its roof as the terreplein. On the northern end there was already a one-story structure, so a second story was added to create the northern extension. The ramp to the top was also built at this time.

A barracks makes up the southern end of the Castillo San Cristóbal cavalier, San Juan National Historic Site

Raising the height of the cavalier required constructing a new terreplein and parapet, which is the wall soldiers stand behind for protection when shooting guns or artillery at the enemy. And of course there has to be embrasures, which are holes or gaps in the parapet to shoot out from—gaps in this case. Fifteen embrasures were added on the east wall and two on the north wall. If the original cavalier was simply used as an observation tower, it was now most certainly outfitted to be a firing deck.

Parapet and embrasures on the terreplein of Castillo San Cristóbal’s cavalier, San Juan National Historic Site

There are now only fourteen embrasures on the east wall and none on the north wall. Between 1896 and 1897, in anticipation of a possible war with the United States, the Spanish installed an emplacement for an updated gun at the northern end of the cavalier. This most likely accounts for the two missing embrasures on that end of the structure.

The United States, which took control of Puerto Rico after defeating the Spanish in the Spanish-American War (1898), added a fire control tower at the northeast corner of the cavalier during World War II, so that accounts for the missing embrasure on the east wall. Fire control towers were used to spot enemy ships and to help provide firing coordinates for artillery. During the war there would have been some sort of scope inside, and those on duty would mainly have been looking for German U-boats. The tower is open to visitors.

Spanish gun emplacement and American fire control tower on Castillo San Cristóbal’s cavalier, San Juan National Historic Site

View east from the American fire control tower on Castillo San Cristóbal’s cavalier, San Juan National Historic Site

The barracks was mainly used to house artillerymen, and a circular staircase on the southern end leads from the second floor to the terreplein of the cavalier, providing the men with a quick way to the guns if need be. Visitors to the fort are welcome to climb the staircase, which is quite narrow. To do so from the plaza, enter the barracks through the central door and proceed up the staircase to the second floor, then head south. If you get to the end of the building and don’t see the stairs, you went the wrong way. The entrance on the terreplein to the staircase is the dome-shaped structure on the southern end of the cavalier.

Staircase from the barracks to the terreplein of Castillo San Cristóbal’s cavalier, San Juan National Historic Site

Staircase entrance on Castillo San Cristóbal’s cavalier, San Juan National Historic Site

The only other modification to the cavalier is a signal house built by the Spanish sometime between 1785 and 1836. This is the small building on the north end near the fire control station.

Signal house installed by the Spanish on the Castillo San Cristóbal cavalier, San Juan National Historic Site

In addition to its history, the cavalier is a great place for views of the rest of the fort and of Old San Juan in all directions.

View of the fort plaza from Castillo San Cristóbal’s cavalier, San Juan National Historic Site

View of San Juan’s harbor from Castillo San Cristóbal’s cavalier, San Juan National Historic Site

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