Gállego River through Biescas Nature · Biescas, Alto Gállego, Huesca Stretch of the río Gállego that runs through the Tena valley and the municipality of Biescas, cutting through the outer ranges at the Foz de Santa Elena. It lies along a former glacial valley that is now a river valley, with the village rising on both sides of it. The headwater section of this stretch, known as the Ribera de Biescas, is protected as a special area of conservation (ZEC) for its environmental value. Photo: Willtron (Wikimedia Commons) (CC BY-SA 3.0) What to see and do in Biescas