Castillo de los Luna de Mesones de Isuela is one of Aragón's largest castles by surface area, crowning a rocky outcrop overlooking Mesones de Isuela in Zaragoza province. Archbishop Lope Fernández de Luna ordered its construction in 1379 as a Gothic-style fortress-palace, though the Order of the Temple held the site from its first documented reference in 1175 until the 14th century, when it transferred to the Fernández de Luna noble family. This rectangular structure measures 68 by 35 metres, built in limestone and flanked by six circular towers, blending defensive and palatial residential functions with remarkable structural regularity and unified monumental design. Declared a National Monument in 1931, the castle represents a unique example of Aragonese military architecture demonstrating modifications to terrain for symmetry and organised courtyard spaces.
