Castle of Frias

Spain, Spain

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Castle of Frías, known as Castillo de los Duques de Frías, is a striking 9th- to 15th-century medieval fortress perched on a rocky hilltop overlooking the Ebro River and Tobalina Valley in Frías, Burgos province, Spain.

Originally built to defend Castile's border with Navarre during repopulation under Alfonso III, it features a robust homage tower, irregular courtyard, corner turrets, moat, crenellated walls, and rare 13th-century Romanesque mullioned windows with carved capitals depicting warriors and mythical birds.

Rebuilt and gifted to the powerful Velasco family—who became Dukes of Frías—it served military purposes through the Napoleonic era before becoming a well-preserved cultural monument open to visitors amid the town's fairy-tale medieval streets and fortified bridge.