Las Miédolas Monument · Las Omañas, Astorga, León An open-cast Roman gold mine at Las Omañas, province of León, smaller than the Médulas of El Bierzo but no less interesting, as it preserves examples of two of the three main methods used to extract gold in the north-west of the peninsula: comb or furrow ploughing, which used water to concentrate gold-rich sediment, and trench-and-channel working, with steeper furrows to carry off ore lying deeper down. This mining, which the Astures had already panned for in the river's placers, was supplied by a network of more than fifty kilometres of Roman channels that brought water from the sierra del Suspirón, more than twenty kilometres away. Photo: Vrei.es (CC BY-SA 4.0) What to see and do in Las Omañas