Castillo de Monreal Monument · Monreal/Elo, Prepirineo, Navarra Of the medieval castle of Monreal, which once hosted royal courts and illustrious prisoners, only ruins remain following its demolition in 1521 by order of the Castilian monarchs; recent excavations have brought to light the keep and a cistern. demolido en 1521 Photo: JLVwiki (CC BY-SA 4.0) What to see and do in Monreal/Elo