Hillfort of a Medoña Nature · San Xoán de Río, Terra de Trives, Ourense Image of San Xoán de Río, not of the place itself. Castro settlement in the parish of Castrelo where remains of a wall survive and where pottery has come to light, evidence of prolonged occupation at this headwater of the Navea. Photo: xolopi (CC BY 3.0) What to see and do in San Xoán de Río