Cave of Altxerri

Altxerri is a karst cave in the municipality of Aia, in the Gipuzkoa province of the Basque Country, Spain. The site is best known for its prehistoric rock art, which has drawn the attention of archaeologists and Paleolithic art researchers since its discovery in the early 1960s.

Where is the cave located?

The entrance to Altxerri sits on a hillside near the valley of the Oria River, close to the coastal town of Orio, although the site itself falls administratively within the municipality of Aia. This stretch of the Basque coastline is riddled with limestone formations, where water has carved out corridors and chambers over thousands of years — a landscape typical of the karst terrain found across this part of Gipuzkoa.

What can visitors expect to see?

The cave is divided into two main sections, separated by a stretch of passage, and researchers treat them as distinct zones with different sets of imagery. The upper area is dominated by depictions of Ice Age fauna — bison, horses and deer, rendered through a mix of engraving and painting. Deeper in, in the lower section, archaeologists identified figures that some specialists interpret as fish or marine creatures, an unusual subject for European cave art that continues to fuel debate over the age and meaning of these images.

The finds at Altxerri placed the cave among the most significant Paleolithic art sites in the Basque Country, alongside nearby Ekain and Santimamiñe. Because the paintings and the cave's microclimate are highly sensitive, access is strictly controlled and generally limited to scientific research and organized educational visits.

How do you get there?

Aia lies inland from the Bay of Biscay coastline, roughly a dozen kilometers from San Sebastián. Driving is the most convenient option, with the route running through the green, hilly countryside typical of the Basque interior. The area is not heavily geared toward mass tourism, so it's worth checking local trail markers in advance for the path leading up to the hillside where the cave entrance is found.

What else is worth seeing nearby?

The countryside around Aia and the Oria valley is largely rural — pastures, woodland and small farms characteristic of the Basque hinterland. Nearby Orio itself is worth a stop, a coastal town with a beach and a working fishing harbor, and travelers interested in prehistoric art can combine a visit with other decorated caves in the region, together forming something of a trail through Gipuzkoa's Paleolithic heritage.

When is the best time to visit?

Spring and early autumn are the most comfortable seasons for exploring the area, with mild temperatures in the Basque interior and the green hills at their most scenic. Summers can be humid, which is worth factoring in if you're planning to walk up to the hillside where the cave entrance lies.

Frequently asked questions

Can you go inside the Altxerri cave? Access to the interior is restricted to protect the paintings and the cave's microclimate — visits are mainly organized for scientific research or educational groups by prior arrangement.

What makes Altxerri different from other Basque painted caves? Its division into two zones with distinct imagery stands out, including rare marine-themed figures alongside the more typical depictions of bison, horses and deer found in regional Paleolithic art.

How far is Altxerri from San Sebastián? The municipality of Aia is about a dozen kilometers from San Sebastián, making it an easy addition to a day trip around the Gipuzkoa region.

Is there anything else worth seeing nearby? Yes — the nearby town of Orio, with its beach and fishing harbor, along with other Paleolithic art sites in the region, make for an interesting combined itinerary for anyone drawn to archaeology and the Basque coastal landscape.