Castle of Alaejos in Valladolid was commissioned around 1453 by Alonso de Fonseca y Ulloa, bishop of Ávila and later archbishop of Seville. The fortress gained historical prominence as the imprisonment site of Queen Juana de Portugal, wife of Enrique IV of Castile and mother of Juana la Beltraneja. Originally constructed with significant architectural presence, the castle now exists largely as underground ruins that have been adapted as a visitable archaeological site open to the public. Privately owned but designated with generic heritage protection, the remains provide insight into 15th-century Castilian military and royal architecture.
