You don't need to be religious to enjoy the serene atmosphere of Jaca Cathedral. Check when the next mass is scheduled or when it's open for general viewing.
You can keep your wallet safely stashed away, because it doesn't cost a penny to wander around Jaca Cathedral. Located in Jaca, you'll find some worthwhile attractions close to this principal church. Why not explore Ciudadela, Diocesan Museum of Jaca - Romanesque Art and Clock Tower too?