The cave of Llonín is not one you can walk into. It sits in the valley of the river Cares in Peñamellera Alta, in the far east of Asturias, and it is one of the decorated Palaeolithic caves of northern Spain listed by UNESCO alongside Altamira. Its walls hold engravings and paintings of deer, goats and other animals, and the cave has been studied by archaeologists for decades, but access is restricted to protect the art. What you get instead is the landscape that sheltered those artists, and that is very much worth the trip.
This is the eastern gate of the Picos de Europa. The limestone walls rise sharply on both sides of the Cares and Deva rivers, green with oak, chestnut and hazel lower down and bare grey rock higher up. The roads around Panes and Alles are narrow and twisting, following the river bends and climbing in places to small villages perched on terraces. The surface is mostly good but can be damp and mossy in the shade, and fallen stones are not unusual after heavy rain. Traffic picks up in summer, especially on the main road through the Hermida gorge towards Potes, a deep, dark canyon where the road and river squeeze between cliffs for kilometres.
The Cares valley is also cheese country. Cabrales, the pungent blue cheese ripened in limestone caves, is made in the villages just to the west, and the local cider is excellent with it. Llanes, on the coast about thirteen kilometres away, is the largest nearby town, with a lively harbour, beaches and every kind of service, while Panes, much closer, has shops, bars and fuel for the immediate needs.
Potes, about twenty kilometres to the south east, is the main town of Liébana and the gateway to the monastery of Santo Toribio, which holds what is said to be the largest surviving fragment of the True Cross. Combining the caves, the gorge and the monastery makes for a classic loop. The weather here is changeable at best, with Atlantic rain and mountain fog arriving quickly, and the high roads into the Picos can be closed by snow in winter. Ride early in summer to beat the crowds and the haze.