Castillo del Compromiso

Castillo del Compromiso is a medieval castle in Caspe, a town in the province of Zaragoza in Aragon, best known as the site where the succession to the Crown of Aragon was settled in 1412.

What happened at the castle in 1412?

When King Martin I "the Humane" died in 1410 without a legitimate heir, the Crown of Aragon — then made up of Aragon, Catalonia and Valencia — was left without a clear successor. To avoid a civil war, a commission of nine "compromisarios" was formed, three representatives from each of the three territories. They met in the castle's throne room in Caspe, and on 28 June 1412 they announced their verdict: the crown would pass to Ferdinand I of Antequera, of the Castilian house of Trastámara. The episode became known as the Compromiso de Caspe and is remembered as an early example of a dynastic dispute settled through negotiation rather than armed conflict, at a time also marked by rival loyalties to the Avignon pope Benedict XIII during the Western Schism.

What is the history of the building itself?

The fortress predates the events of 1412 by centuries — the earliest fortifications on the site go back to the early Middle Ages. For a long period it belonged to the Order of the Knights of St John of Jerusalem and served as the residence of the order's bailiff, which is why it is also referred to as the Castillo de la Bailía. Over the centuries the building was repeatedly altered and rebuilt to suit successive owners' needs.

The 19th century was particularly destructive for the castle. During the Peninsular War, French troops blew up part of the monastic buildings attached to the castle complex. Later, during the Carlist Wars, the site saw fighting and suffered a fire, leaving it in ruins for a long time afterward.

What does the castle look like today?

The Castillo del Compromiso's current appearance is largely the result of restoration work completed in 2012, timed to mark the 600th anniversary of the Compromiso de Caspe. As part of that project, the throne room — also known as the "Room of the Compromiso," where the delegates deliberated and announced the new king — was rebuilt. That room remains the highlight of any visit and the symbolic core of the castle today.

How can visitors tour the castle?

The castle is open Tuesday to Sunday. On weekdays (Tuesday to Saturday) it can be visited between 12:30 and 13:15, and on Sundays between 11:30 and 12:15. Access is via guided tours departing from the Caspe Tourist Office — at 11:00 from Tuesday to Saturday, and at 10:00 on Sundays. A guided visit lasts around 45 minutes and costs 2.20 euros. Because group sizes are limited, it's worth booking ahead through the local tourist office.

Why is Castillo del Compromiso worth visiting?

The site offers a rare combination of genuine historical weight and a compact, easy-to-tour scale. For anyone interested in Spanish history and the old Crown of Aragon, this is one of the essential stops — the place where the dynastic future of the entire region was effectively decided for generations to come, and one that can be toured in under an hour, easily combined with the rest of what Caspe, set beside the Mequinenza reservoir, has to offer.

Frequently asked questions

What was the Compromiso de Caspe? It was the decision reached on 28 June 1412 by nine delegates representing Aragon, Catalonia and Valencia, which placed Ferdinand I of Antequera on the throne of the Crown of Aragon.

Has the castle survived in its original 15th-century form? Not entirely — the building was damaged during the 19th century, including during the Peninsular War and the Carlist Wars, and its current appearance is mainly the result of a restoration completed in 2012.

How long does a visit take and how much does it cost? A guided tour lasts about 45 minutes and costs 2.20 euros.

Where do the guided tours start? From the Caspe Tourist Office — at 11:00 Tuesday to Saturday, and at 10:00 on Sundays.