For at least 300 years, the rumors have persisted: beneath the streets of Guadalajara, there is a vast network of tunnels; these connect many important buildings in the city, such as churches and convents, mansions and monuments, chapels and cemeteries; the tunnels are wide and high enough to accommodate horses and even carriages.
They say the “Father” of the Revolution, Miguel Hidalgo, used the tunnels to escape his enemies and that Benito Juárez found them handy for getting around the city unnoticed.
An investigation into these mysteries, carried out in 2013 by Dr. Alicia Torres Rodríguez of the University of Guadalajara, revealed that the legendary “tunnels of Guadalajara” are actually galerías filtrantes—underground aqueducts constructed throughout the colonial period to bring potable water into the city.
Most qanats under Guadalajara look like this.
Most of these aqueducts, says Torres, “owe their origin to a Franciscan friar named Pedro Buzeta.”
In the 1700s, the city faced a desperate water shortage. When city leaders learned that a Spanish friar had successfully engineered a water supply for Veracruz, they summoned him. Buzeta soon determined that water could be sourced from the north and southwestern edges of Guadalajara, and that the best delivery method was not an above-ground aqueduct but a gravity-based filtration gallery — a 3,000-year-old technology originating in Persia.
This underground aqueduct is widely known by its Arabic name: qanat.
How to dig a qanat
To dig a qanat, technical experts called muqannis first trace a straight line above ground between a water source and the distant site where water is needed. At regular intervals along this line, workers dig narrow shafts less than a meter wide down to a precise, varying depth.
Next, they connect these shafts underground, creating a tunnel roughly two meters high and one meter wide with a gentle downward slope of less than two degrees.
The final, perilous step is connecting the tunnel to the water source. If done incorrectly, the worker risks death.
Once water flows through the filtration gallery, all access shafts are covered with flat stones to keep the qanat clean and reduce evaporation. This technology proved immensely successful and was adapted by civilizations from the Arabs and Romans to the Chinese and Spanish, who brought it to Mexico. While most qanats are under five kilometers long, some exceed 70 kilometers.
‘This is not a cave!’
For many years, I was a cave explorer in western Mexico, which led to my first encounter with a qanat in the hills above the town of La Venta del Astillero, west of Guadalajara.
At first, my group of speleologists believed we had discovered a peculiar, long cave with about 70 small openings in the roof, spaced precisely 11 meters apart in a straight line. The beams of light they created were both picturesque and useful. However, when we invited archaeologist Phil Weigand to inspect it, he immediately corrected us: “John, this is not a cave — it’s a qanat!”
Once we recognized the pattern, we discovered several more qanats in the area.
Mysterious tunnel
Then came a tantalizing request from the director of a tree farm at the northwestern edge of Guadalajara.
“There’s a kind of well on our property with iron rungs leading down to a locked gate,” he said. “Behind the gate, there’s a long tunnel. Can you tell us what this is?”
For cavers, such a request is an irresistible call to adventure. We arrived equipped with lights, helmets, and survey gear.
“Inside that tunnel, did you notice any small holes in the roof?” I asked.
“No, I didn’t,” the director replied — which surprised me.
We clambered down the rungs. The director unlocked the gate, and we found ourselves at the mouth of a long, straight tunnel just over a meter wide and nearly two meters high. It wasn’t spacious enough for a carriage, but perhaps for a small horse. The walls and curved roof were made of brick and in remarkably good condition. Water flowed along a channel to the right.
“This looks suspiciously like a qanat, and a very elegant one at that,” I told him.
We began our survey. Exactly 100 meters from the start, we found an opening above our heads: a vertical shaft with footholds, leading up to a manhole cover with sunlight piercing through.
Every 100 meters, we found another identical shaft — the definitive signature of a qanat.
Every 100 meters, there is a vertical shaft leading to the surface,
After 300 meters, our passage emptied into a large, round pool. On the far side, we could see similar tunnels branching off into the darkness.
Underground pools like this mark the junction of several qanats.
The truth was now undeniable: we were inside the legendary network of qanats built under the supervision or inspiration of Friar Buzeta.
Crumbling qanats
Dr. Torres estimates that by the early 20th century, Guadalajara was supplied by nine lines of filtration galleries stretching up to 20 kilometers in total length.
Amazingly, these qanats — built between 1731 and 1895 — still supply a substantial amount of water to the city.
Unfortunately, their precise locations are now largely unknown. “They have been abandoned,” says Torres, “and are beginning to crumble.”
A fact worth remembering, should anyone ever invite you on an underground tour of Guadalajara.