Everyone talks about Altamira, but Monte Castillo has a better claim to the title of Europe's oldest gallery. El Castillo, the cave that gives the hill its name, contains a red disc that was dated in 2012 to more than forty thousand years ago, which makes it among the oldest known cave paintings anywhere. Las Chimeneas, the cave marked here, is one of its neighbours inside the same hill, and the whole mountain is a kind of honeycomb of Ice Age art.
The Chimeneas cave takes its name from the vertical shafts, the chimneys, that connect its galleries, and its walls hold animal drawings and a good number of the tangled finger lines that archaeologists call macaronis, made by dragging fingers through soft clay. It is a dark, narrow place, and the guides who take small groups through it do so with a care that tells you how fragile it is. Bookings are essential, and the number of visitors per day is deliberately small, so look up the arrangements before you set out.
Monte Castillo is a limestone cone rising straight out of the Pas valley, and the village of Puente Viesgo sits at its foot, famous since the eighteenth century for its warm mineral springs, which still feed a spa. The river here runs clear over round stones, and the oaks and chestnuts on the slopes shade the road. In the morning mist drifts down the valley and lies in the meadows like milk.
Riders will want to continue up the valley. The road climbs from Puente Viesgo toward the Puerto del Escudo, one of the classic Cantabrian passes, with a long series of curves, steep green slopes, and views that open out once you clear the forest. The surface is mostly good, though wet and slippery in the damp weather the region is known for. Early autumn gives the best compromise of dry days and quiet roads.
Fuel is available in Torrelavega, a town of fifty-five thousand, about nine kilometres from the cave, and Puente Viesgo itself has bars and a few restaurants.