Fuerte de San Cristóbal sits on Mount Ezkaba, 892.8 meters high and about 4 kilometers north of Pamplona, and it was built to defend the city with artillery. It never fired on an enemy. By the time construction finished in 1919, military aviation had already made a buried hilltop fort obsolete, and the building that took 41 years to complete found its place in history for something else entirely: on the night of May 22, 1938, 795 prisoners broke out of it in the largest mass prison escape in Spain’s history, and one of the largest in Europe’s.
Most English language coverage of the fort stops there, treating it as a grim true crime footnote from the Spanish Civil War. That framing misses two things worth knowing if you are standing in Pamplona’s old town. First, the fort is not some obscure ruin: it is visible from the city walls, close enough that Ernest Hemingway wrote it into The Sun Also Rises as a detail his characters noticed on a night walk along the ramparts. Second, it is not sealed off. A marked trail leads to it from the edge of the city, and you can walk the perimeter of the fort itself in an afternoon.
This account draws on the Ayuntamiento de Pamplona’s own historical record, Navarra’s regional government archive on the fort’s use as a prison, and cross checked casualty figures from Spanish language academic and press sources, since English language accounts of the escape frequently repeat rounded or unsourced numbers.
A Fort Built for a War That Never Came
Construction began in 1878, two years after the end of the Third Carlist War (1872 to 1876), a conflict that had exposed a real vulnerability in Pamplona’s defenses. Carlist forces had used the high ground ringing the city, including Mount Ezkaba, to shell Pamplona with artillery while the Liberal government held the city itself. That war, and Navarra’s central role in it, is covered in full in our account of the Carlist Wars and Navarra’s fueros. Spanish military planners responded by fortifying the peaks around several vulnerable cities. Fort San Marcos, near San Sebastián, is a comparable project from the same era.
The fort was formally named Fuerte de Alfonso XII after the reigning king, though almost everyone in Pamplona calls it by the mountain it sits on: Fuerte de San Cristóbal, or simply Ezkaba. It took until 1919 to finish, 41 years after the first stone was laid. Most of the structure is buried directly into the mountain rather than built up from it, which is why it is barely visible from a distance despite its scale: three underground floors covering roughly 180,000 square meters, ringed by a moat, inside a total military site of 615,000 square meters.
The delay proved fatal to the fort’s purpose. Artillery forts built to control high ground made sense in the 1870s. By the 1910s, military aircraft could simply fly over a fixed hilltop position, and the entire concept behind San Cristóbal was already outdated before the last stone was set. The fort never engaged in the kind of combat it was designed for. Instead, within a decade of its completion, the Spanish state found an entirely different use for it.
From Military Fort to Political Prison
In 1929 the fort was converted into a military prison, and by 1931 it was operating as a full provincial penal institution. Its first large intake came after the October 1934 revolutionary uprising centered in Asturias, when several hundred convicts, many of them miners and organizers from Asturias and the Basque town of Eibar, were sent to San Cristóbal. Conditions were bad enough that a prisoner’s death in September 1935 triggered strikes across Pamplona. Most of that population, around 400 people, was released under the February 1936 amnesty that followed the Popular Front’s election victory.
The reprieve did not last. After the July 1936 military coup, Navarra fell under Nationalist control, and the prison filled again almost immediately, holding more than 2,000 people within months. Some men were told they were being released, only to be shot as they walked down the mountain. By 1938, the fort held roughly 2,500 prisoners, most of them Republican political and union figures transferred from across Spain, a large share of them from Castile and Galicia after the Nationalist army took the Northern Front.
Conditions inside were severe: overcrowding, chronic malnutrition, lice, and beatings were routine. The fort also functioned as a de facto tuberculosis ward, receiving sick prisoners transferred in from other jails. Navarra’s own regional archive on the fort documents 305 prisoner deaths between January 1937 and the fort’s 1945 closure, most attributed to malnutrition, cardiac failure, or tuberculosis. A number of these deaths were recorded in the prison ledger with vague causes like “trauma,” a label later established to have concealed executions, including 21 prisoners shot on November 1, 1936, and four more shot on November 17 of that year.
The Escape of May 22, 1938
The escape was planned by a core group of about thirty prisoners, who reportedly communicated using Esperanto so guards could not follow their preparations. They moved on a Sunday evening, timed to the dinner hour, when the fort’s roughly 92 military guards were dispersed and eating rather than standing watch. Prisoners disarmed guards in small groups; one soldier who resisted was killed with a blow from a bar, and the remaining sentries surrendered without further resistance. The prisoners controlled the fort within about half an hour.
The escape unraveled almost immediately. A soldier returning to Pamplona spotted the breakout in progress and ran to raise the alarm in the city. A Falangist prisoner named Ángel Alcázar de Velasco, who had been jailed for unrelated events in Salamanca the previous year, also ran down the mountain to alert the authorities, and had his own sentence reduced as a result. As military trucks with searchlights approached the fort, some prisoners abandoned the escape outright. A headcount taken at 3:30 a.m. found 1,692 prisoners still inside, meaning 795 had gone over the wall: poorly clothed, malnourished, carrying only a handful of rifles between them, with no coordinated escape route.
What followed was a manhunt across the mountains north of Pamplona. Nationalist forces captured 259 escapees by the next day and 445 within two days. Of the 795 who escaped, 585 were eventually recaptured, and only three reached the French border and freedom. The last man at large was not caught until August 14, nearly three months later; he was nicknamed “Tarzán” for surviving alone in the mountains that long. Cross checked sources place the number who died as a direct result of the escape at roughly 220, though figures reported in different accounts range from about 206 to 221 depending on whether deaths among later recaptured prisoners are counted alongside those killed during the manhunt itself. Of the 585 captured, seventeen were tried as ringleaders. Fourteen were sentenced to death and shot at Vuelta del Castillo, just behind Pamplona’s Ciudadela, on September 8, 1938.
The Fort Hemingway Could See From the City Walls
Ernest Hemingway spent enough time in Pamplona in the 1920s to know the geography around it in detail, and Mount Ezkaba made it into The Sun Also Rises. In a night scene along the city’s ramparts, the narrator describes looking out over the plain: “We looked out at the plain. The long lines of trees were dark in the moonlight. There were the lights of a car climbing the road of the mountain. Up on the top of the mountain we saw the lights of the fort.”
The Ayuntamiento de Pamplona’s own historical account of the mountain confirms the identification directly: the fort Hemingway’s characters see from the walls is Fuerte de San Cristóbal. It is a detail almost never mentioned in English language writing about the escape, even though the two facts sit right next to each other: the same fortress that dominates one of the twentieth century’s most notorious prison breaks is also a fixture of the most famous novel ever written about Pamplona, a connection covered in more depth in Encierro’s own account of Hemingway’s time in Pamplona.
That connection is easy to verify for yourself. Stand on Pamplona’s city walls near the Ciudadela on a clear night and look north. The lights on Mount Ezkaba that Hemingway’s characters noticed almost a century ago are still there.
Visiting Ezkaba Today
The fort’s interior remains property of Spain’s Ministry of Defense, and it is not open for casual walk-in visits. The last permanent military detachment left in 1991, and the site has sat abandoned since, aside from a brief and unauthorized stint as a poultry farm in the 1990s. It was declared a Bien de Interés Cultural, a protected heritage site, in 2001. Restoration work funded by the Spanish Congress removed the prison era interior walls and kitchen between 2007 and 2009, and limited guided visits to the interior have been arranged through Navarra’s regional government since June 2009, though the current schedule should always be confirmed directly before planning a trip around it.
What is reliably open is the mountain itself. A marked trail circles the fort’s perimeter along its moat, and a straightforward circular hike from the Pamplona neighborhood of Artica covers about 7 kilometers round trip in 2 to 2.5 hours at an easy pace, an approachable route even with children. Along the way it passes a small cemetery honoring those who died at the fort, a viewpoint at the Sagrado Corazón statue overlooking the Pamplona basin, and a 1988 memorial sculpture dedicated to the men who escaped, before circling the fort itself at the summit.
For a longer, harder version of the same story, the GR-225 long distance trail retraces roughly 53 kilometers of the escapees’ actual route toward the French border, with about 2,175 meters of elevation gain along the way. Most hikers take 18 to 20 hours to complete it, typically spread across two days. It is not a casual outing, but it is the closest thing to walking the escape itself, through the same terrain the 795 men crossed with no maps, no supplies, and almost no chance of reaching the border they were running toward.
Frequently Asked Questions
Can you visit Fuerte de San Cristóbal in Pamplona?
You cannot freely enter the fort’s interior, since it remains Ministry of Defense property, though limited guided visits are arranged through Navarra’s regional government at certain times of year. What you can always do is hike the marked trail that circles the fort itself from the Pamplona neighborhood of Artica, a round trip of about 7 kilometers that takes 2 to 2.5 hours.
How many prisoners escaped from Fuerte de San Cristóbal in 1938?
795 prisoners escaped on the night of May 22, 1938, in what remains one of the largest prison breaks in European history. Only three of them successfully crossed into France; the rest were recaptured or killed in the manhunt that followed, with the death toll from the escape estimated at roughly 220.
Is Fuerte de San Cristóbal the fort mentioned in The Sun Also Rises?
Yes. Hemingway’s novel describes a night scene on Pamplona’s city walls in which characters see “the lights of the fort” on top of the mountain across the plain, and the Ayuntamiento de Pamplona’s own historical record confirms this is Fuerte de San Cristóbal on Mount Ezkaba.
How do you hike to Fuerte de San Cristóbal from Pamplona?
The most accessible route starts in the Artica neighborhood on the edge of Pamplona and follows a marked path with red and white GR waymarking, covering about 7 kilometers round trip in 2 to 2.5 hours. Hikers looking for a longer route can follow the GR-225, a 53 kilometer trail that retraces the escapees’ path toward the French border.
Every article on the Encierro blog is authored or reviewed by active bull runners with direct experience in Pamplona.