The Roman bridge of Puentes del Alagón Monument · Santibáñez de la Sierra, Sierra de Francia, Salamanca Erected in the first century BC over the Alagón, it is one of the oldest bridges on the peninsula. Beside it is another of medieval appearance over the Saltillo, and between the two stretches of the original paving of the Roman road are preserved. Photo: P nx (CC BY-SA 3.0) What to see and do in Santibáñez de la Sierra