Underground Cartagena: Tunnels, Cisterns and Secret Passages of the Walled City

Origins

The Cartagena that tourists walk through — the one with walls at sunset and balconies covered in bougainvillea — is only the upper layer of a city that, for nearly three centuries, was also conceived downward. Not out of mystery or legend, but for a very concrete reason: water. Cartagena de Indias was founded in 1533 on a geography of lagoons, channels and marshes, and during the colonial era access to fresh water was as strategic as the cannons of its forts. That is where the aljibes came from: large masonry reservoirs that collected rainwater and supplied the population when corsair sieges cut off the supply from land.

And it must be said from the outset, because there is a lot of myth circulating online: there are no secret Cold War tunnels in Cartagena, no hidden bunkers beneath the hills, and no clandestine passages connecting convents with fortresses. Those stories are repeated in blogs and on some informal tours, but they have no documentary or archaeological support. What does exist — and is fascinating — is a real, visible and largely visitable hydraulic infrastructure: aljibes, cisterns, wells and the underground galleries of the military batteries of Castillo San Felipe de Barajas. In this verified Malokal guide you will find the practical details for each spot; use the interactive cards for each place on malokal.com to check the safe neighborhood map (Locals vs. Foreigners), live holiday hours and book directly via WhatsApp.

The walled city that visitors walk through today is, to a large extent, the Cartagena rebuilt after the siege of the Baron de Pointis in 1697 and the defensive reforms of the 18th century. Beneath those streets, the system of aljibes and cisterns kept working well into the 20th century, when the modern aqueduct arrived. Today those spaces are living memory of colonial ingenuity, and exploring them is one of the most honest ways to understand why Cartagena was, for so long, a besieged city.

Timeline and historical milestones

1533–1586: the city that learned to store water

From the founding by Pedro de Heredia, water supply depended on domestic aljibes and on the waters that came from the foot of the Cerro de La Popa and the nearby channels. The first cisterns were built inside houses and in convent courtyards, and they became an architectural element inseparable from daily life. Anyone walking today through the Centro Histórico and seeing a stone wellhead in an inner courtyard is almost always looking at a disused colonial aljibe.

1586: the siege of Francis Drake

The attack by the English corsair Francis Drake put the city to the test and left a clear lesson: without water, there is no resistance. From then on, the Spanish Crown promoted defensive works as well as hydraulic ones. The aljibes ceased to be a private matter and became collective survival infrastructure.

1697: the siege of Pointis and the reconstruction

The sack by the Baron de Pointis devastated much of the city. The 18th-century reconstruction not only raised more solid walls and the imposing Castillo San Felipe de Barajas, but also reinforced the cistern system. The Cartagena that is walked today is, in large part, a child of that reconstruction. And this is worth pausing on: when the besiegers cut off the supply from land, it was the cisterns of courtyards and convents that sustained the population. The water stored beneath the feet of the people of Cartagena ended up weighing as much as the walls that surrounded them.

18th century: Castillo San Felipe de Barajas and its galleries

The castle, the crowning work of Spanish military engineering in the Americas, was expanded during the 18th century until it became the largest fortress on the continent. Beneath its batteries a network of galleries was built — vaulted masonry passages — that served to connect positions, store ammunition and evacuate troops. These galleries do exist and can be visited, although they are not "secret tunnels" in the romantic sense: they are documented military works, designed by engineers such as Antonio de Arévalo.

19th–20th century: the decline of the aljibe and the arrival of the aqueduct

With independence and, later, with the urban modernization of the 20th century, the aljibes lost their function. Many were sealed, others became storage tanks or planters, and some remained beneath the floors of houses. The memory of underground water faded, but it did not disappear: today it is being studied again as heritage.

Key figures and events

Antonio de Arévalo

The Spanish military engineer responsible for much of the defensive works of the 18th century in Cartagena, including the expansion of Castillo San Felipe de Barajas. His work was not only about walls and cannons: he also planned galleries, warehouses and internal communication systems for the fortress. If today you can walk through the underground passages of the castle, it is largely thanks to his design.

Las Bóvedas

Las Bóvedas, that set of semicircular arches embedded in the wall of the San Diego neighborhood, were built at the end of the 18th century as military warehouses and, depending on the period, also as cells. Their name refers precisely to the barrel vaults that support the galleries. Today they are a corridor of crafts and workshops, but their architecture — thick walls, calculated ventilation, controlled humidity — recalls their origin as a semi-buried space. Legend has also been woven here: it is said that a passage connects them with the castle. The reality is less novelistic and more solid: what exists is a continuous wall and a coherent defensive system that can be read on foot.

The convent aljibes

Convents such as San Pedro Claver or Santa Clara kept their own cisterns for centuries, some of them of great capacity. In the case of the convent of San Pedro Claver, the memory of water is intertwined with the life of the Jesuit saint who defended enslaved people in the 17th century. These spaces, today museums or hotels, allow you to see original wellheads and reservoirs in inner courtyards.

Tunnels of Castillo San Felipe de Barajas

This is the point that generates the most confusion. The castle's galleries are real, documented and part of the tourist route. They are vaulted passages that connected different points of the fortress and are now explored with a guide. Legend, on the other hand, insists on a tunnel that would reach the Centro Histórico or the convent of La Popa: there is no support for such a layout. The value of these galleries is military and architectural, not esoteric.

Cisterns and aljibes of the Centro Histórico de Cartagena

Scattered through the courtyards of colonial houses, boutique hotels and some museums, the aljibes of the center are the city's most silent trace. Many establishments have integrated them as a decorative element or turned them into small pools. For the curious traveler, the recommendation is simple: when you enter a courtyard and see a circular stone wellhead, ask. There is almost always a story behind it.

Current status

What you can visit today (and what you can't)

The good news for anyone seeking underground Cartagena is that what is verifiable is also the most interesting. Castillo San Felipe de Barajas offers a tour of its underground galleries, with local guides who explain the defensive system. Las Bóvedas can be walked through along its crafts corridor. And in the Centro Histórico, several museums and hotels allow you to see original aljibes in their courtyards. On the other side are the stories repeated without evidence: tunnels between convents, Cold War bunkers, passages beneath the hills. If a tour offers you "the secret tunnel of the Jesuits," be wary: it is marketing, not history.

To plan your visit, keep in mind that hours and rates change by season and holidays. In this Malokal guide you can check reference prices for October 2026 and use the interactive cards for each place on malokal.com to see the safe neighborhood map, live hours and book via WhatsApp. Guided tour price ranges usually fall between budget and moderate, and many museums in the center have reduced rates on certain days; it is worth verifying before you go.

How to explore with respect for heritage

Cartagena is a World Heritage Site and its underground spaces are fragile. Some practical recommendations: do not touch the masonry walls of the castle galleries (humidity and salts deteriorate them), do not enter private aljibes without permission, and avoid tours that promise "exclusive access" to unauthorized places. The best way to get to know the underground city is with certified local guides and respectful curiosity.

The hidden map of Cartagena

More than a labyrinth of secret tunnels, underground Cartagena is an archive of engineering: aljibes that stored water in times of siege, galleries that connected batteries, cisterns that are now gardens. Exploring it is understanding that this city defended itself with cannons as much as with stone and water. And that its deepest history is not hidden in impossible passages, but in plain sight for those who know how to look at a wellhead in a courtyard or a vault in the wall.

Download our interactive map of visitable underground sites at malokal.com and plan your route: castle, bóvedas and aljibes of the center in a single day, with stops to eat in the San Diego and Getsemaní neighborhoods. The city awaits you, downward too.