There is a Cueva de los Moros in half the valleys of Spain. Every unexplained cave, ruin or rock shelter used to be credited to the Moors, and this one, in the hills of the western Aragonese Pyrenees between the valleys of Hecho and Ansó, is a rock shelter with ancient traces. You should approach it as an excuse to spend time in two of the most beautiful and least spoiled valleys of the Pyrenees, rather than as a monument.
The Hecho and Ansó valleys run north from the Canal de Berdún toward the French border, and they are full of stone villages with steep roofs, massive chimneys and wooden balconies. Hecho, with about a thousand people, keeps its own dialect, cheso, and Ansó is famous for its traditional costumes, worn at a festival each summer. The upper valleys are wild: the Selva de Oza, a forest of beech and fir at the head of the Hecho valley, and the Boca del Infierno, a narrow gorge where the road squeezes between rock walls above a roaring river.
The roads are narrow, winding and often in good condition, with little traffic outside the summer holidays. The road between Hecho and Ansó crosses a low pass through pine woods, a short and satisfying ride. North, the roads end in the mountains, and there are no passes into France here, so the valleys feel like dead ends in the best sense. Weather in the Pyrenees can change quickly, and snow is common in winter.
For fuel, head south to the Canal de Berdún or east to Jaca, a lively town of over thirteen thousand with a Romanesque cathedral and a pentagonal citadel. Hecho and Ansó have bars, small shops and restaurants serving hearty mountain food like migas, lamb and trout. Spring and autumn are the best times, when the forests are full of colour and the mountains are clear.