Castillo de Castañares de las Cuevas

Spain, Spain

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Castillo de Castañares de las Cuevas is a unique 12th-14th century cave castle ingeniously carved into natural rock grottoes along a barranco in the Sierra de Moncalvillo near Viguera, La Rioja, northern Spain, where defenders exploited sheer cliffs of the Iregua River gorge for impregnable protection.

First utilized possibly in the 10th century after Sancho Garcés II conquered the area from Muslims granting it to noble Fortún Ochoiz and later donated by Queen Estefanía in 1060 to Nájera's monastery, the complex features strong towers adjoined to caves, artificial tunnels, and chambers now largely ruined by rockfalls, including a major collapse in 1931.

Associated with the powerful Zúñiga lineage by the mid-14th century under Iñigo Ortiz de Zúñiga, this rare troglodytic fortress exemplifies La Rioja's innovative medieval defensive architecture blending human engineering with dramatic geology.