Castle-Palace of Pope Luna Monument · Illueca, Aranda, Zaragoza A Mudéjar fortress of the 14th and 15th centuries, the family residence and birthplace of Benedict XIII, the only Aragonese pope, declared a Monumento Nacional (Spain's heritage designation in force until 1931) in 1931. Photo: Miguel Ángel García. from Ólvega., España (CC BY 2.0) What to see and do in Illueca