Bibei Canyon Nature · Viana do Bolo, Viana, Ourense Image of Viana do Bolo, not of the place itself. Before joining the Sil, the Bibei cuts a canyon of some forty kilometres with drops of up to 500 metres; on its slopes terraced vineyards survive, along with one of the oldest riverside woodlands in Spain. Photo: PONTE...NAS ONDAS! (CC BY 2.0) What to see and do in Viana do Bolo