Castle of Alcalá la Vieja (ruins)

Spain, Spain

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Castle of Alcalá la Vieja consists of the ruins of a 9th-10th century Hispano-Muslim fortress situated on a hill overlooking the Henares River near Alcalá de Henares in Spain's Community of Madrid.

Originally constructed as Qal'at Abd-Salam, likely starting as a simple watchtower within the Middle Mark's defensive network, it expanded into a triangular enclosure spanning two hectares with eight towers, including the surviving Alabrana tower, plus internal silos and a barrel-vaulted cistern.

Conquered by Ferdinand the Great in 1053 and recaptured by Muslims the next year, it fell permanently to Christians around 1118 amid repopulation efforts before gradual abandonment from the 15th century, now accessible via marked trails offering panoramic views in the Parque de los Cerros.