The Castillo de las Duques de Frias stands on a rock above the River Ebro and overlooks the Tobalina Valley. Dating from the 12th Century, it was rebuilt in the 15th Century by Alfonso 111 and became a seat of the Fernandezde Velasco family. The castle retains a tower, turrets at the corners of the walls, a moat and a courtyard. There are three windows with 13th Century Romanesque capitals. Visits can be arranged.
