Huesca was the capital of the kingdom of Aragón until the end of the eleventh century, when King Pedro I captured it from the Muslim rulers and made it his base. Today it is a calm provincial city of more than fifty thousand people, with a Gothic cathedral that has a magnificent alabaster altarpiece and the Romanesque monastery church of San Pedro el Viejo. It is the last big town before the mountains, and it is where you will want to fill your tank before heading north into the Sierra de Guara. The shelter at Mascún IV lies about thirty kilometres away, deep in the Mascún valley, about fifteen kilometres from Alquézar. It carries painting in the Levantine tradition, protected by UNESCO as part of the rock art of the Mediterranean basin in Spain, and the ride links it with the Cueva de los Moros.
The valley is one of the quietest and most dramatic in the region. The river has cut a deep gorge, and the cliffs rise on either side, hundreds of metres high, in bands of grey, ochre and orange. The hills above are covered with holm oak, box and pine, and the sound of water echoes in the canyon. In summer, the pools are bright green, and canyoners in wetsuits drop from ledge to ledge. The sense of remoteness is powerful, and the villages, with only a handful of residents, add to it.
The road to the valley is narrow, winding and wonderful, with tight bends, steep drops and views that open without warning. It is lightly used, but the surface can be rough, patched and gravelly, and the last section requires care. Take it slowly, and watch for livestock. Spring and autumn are the best seasons, and winter ice can linger on shaded stretches.
Angüés and Boltaña are very small, so fill up in Huesca, or in Barbastro, before you set out. Carry water, food and a warm layer, and tell someone where you are going if you plan to walk.