Megalithic Complex of Guarrinza Curiosity · Valle de Hecho, La Jacetania, Huesca Image of Valle de Hecho, not of the place itself. Group of dolmens and tumuli in the Guarrinza area, at the head of the Hecho valley (La Jacetania, Huesca), where, together with the Selva de Oza and along the Aragón Subordán river and its tributaries, the highest density of megalithic monuments in the whole Pyrenean range is concentrated. The dolmens and cromlechs of the area date from approximately 3000 BC. Photo: Pelayo 08 (CC BY-SA 4.0) What to see and do in Valle de Hecho