Castle of Curiel de Duero Monument · Curiel de Duero, Campo de Peñafiel, Valladolid It crowns a rocky hill above the village and is considered the oldest castle in the province, with its origin in the tenth century. From the fourteenth century it belonged to the house of Zúñiga and today it works as a hotel of twenty-six rooms. Photo: Juan Pablo Zumel Arranz (CC BY-SA 4.0) What to see and do in Curiel de Duero