The hillforts and pre-Roman walls of Pías Nature · Pías, Sanabria, Zamora Image of Pías, not of the place itself. The municipal district preserves remains of castros and of defensive walls of the pre-Roman period alongside Roman vestiges —bread ovens, fountains and remains of bridges— spread over its forty-three square kilometres. Photo: Estevoaei (CC BY-SA 4.0) What to see and do in Pías