The Caves of Hundered Pillars

The Caves of Hundred Pillars (Cuevas de los Cien Pilares) in Arnedo, La Rioja, form an underground labyrinth carved into the rock beneath San Miguel hill — one of the most extensive cave complexes in the entire Cidacos valley.

What exactly is hidden inside the hill?

The complex is a network of chambers and galleries hollowed directly out of the sandstone, linked by long passages and staircases across four levels. Many of the rooms have ceilings held up by pillars cut from the same rock, which is where the site gets its name. The caves date back to the Middle Ages, when instability in the surrounding valleys pushed local communities to seek shelter in the mountains — or literally inside them. Historians believe one of the chambers may once have housed the rock-cut monastery of San Miguel.

Over the centuries the caves changed purpose. Until the mid-20th century, families from Arnedo used them not as homes but as practical storage space — pantries, cellars, and warehouses that stayed naturally cool and stable regardless of the weather outside. This everyday "life underground" is now the subject of a small exhibition included in the visit.

How do you get there and what does a visit look like?

The caves sit right in Arnedo, at the foot of San Miguel hill, which overlooks the town's old quarter. You can't wander into the complex on your own — access is only possible on a guided tour that departs from the town center. The route winds through successive levels of galleries, revealing the pillar construction and the layout of the chambers, and because group size is limited, booking a spot ahead of time is recommended.

What will you actually see inside?

The visit starts at the Interpretation Center of Cave Life, which lays out the story of Arnedo's cave-dwelling past in brief — from medieval refuge to everyday storage space well into the 20th century. From there, a guide leads visitors through the caves themselves: narrow passages open into wide chambers with vaulted ceilings resting on stone pillars, and staircases connect levels tucked several meters beneath the hill's surface. It's a rare chance to see a structure that grew for centuries not upward, but inward, into solid rock.

When is the best time to visit?

Because the interior temperature stays constant regardless of conditions outside, the caves can be visited comfortably almost any time of year. It's still worth checking the current guided-tour schedule and reserving a slot in advance, since the number of daily visits is limited.

Frequently Asked Questions

Can I visit the caves on my own, without a guide? No — entry to the complex is only possible as part of an organized guided tour that starts from Arnedo's town center.

How long does the visit take? A standard tour covering the caves and the interpretation center runs for around two hours.

Were the caves ever used as actual homes? Not quite — families from Arnedo mainly used them as storage space (pantries, cellars, warehouses) up until the mid-20th century, while earlier, in the Middle Ages, they served as shelter and possibly the site of a rock-cut monastery.

Why are they called the Caves of Hundred Pillars? The name comes from the numerous pillars carved straight out of the solid rock, which support the vaulted ceilings of the chambers spread across the complex's four levels.