Castle of Obano is an 11th-century Romanesque fortress located in Luna, a municipality in Zaragoza's Cinco Villas region. Built during the reign of Sancho Ramírez, this ashlar stone tower measures approximately 9 by 7 meters with walls reaching 15 meters in height. Originally four stories plus basement, the tower once housed a chapel affiliated with the San Juan de la Peña monastery and served as a Templar stronghold after being donated by King Alfonso II. Strategically positioned to monitor communication routes between Huesca and Ejea de los Caballeros along the Arba de Biel river, the castle exemplifies medieval frontier defense architecture in Aragon.
