It is 30 km from Pamplona. It was originally constructed on a rocky hill in the 10th century as an Arab Fortress. However, there is virtually none of the original Arab buildings left. It had the double mission of being a bastion to protect the frontier and also a home for noblemen and knights. In later years it became a place of pilgrimage because was the birthplace of St Francis Xavier (one of the founders of the Society of Jesus or Jesuits) .