405/5000 The Castle of Cea stands on a mound that dominates the town of Cea, in Leon. It was built in the 15th century on an older castle destroyed in the 12th century and which had been built around the 9th century. This primitive castle in turn was built on a castro. It was used as a prison for Navarrese kings and Castilian counts. Https://en.wikipedia.org/wiki/Castillo_de_Cea