Sil terraces in Caldelas Nature · O Castro de Caldelas, Terra de Caldelas, Ourense Stone terraces built on the slopes falling to the Sil in order to grow vines on impossible gradients, a farming landscape that has been maintained since Roman times throughout the Ribeira Sacra. Photo: Antón Méndez Gándara (CC BY-SA 4.0) What to see and do in O Castro de Caldelas