[UNVERIFIED CONTENT] Jaca Citadel had been called the San Pedro (Saint Peter) Castle until the 19th century. It was built from 1595 until the late 17th century, to secure the frontier with France and to prevent the Huguenot army from entering Spain through the Santiago pilgrimage route. The castle was designed by the Italian Knight Commander Tiburcio Spanich in the shape of a pentagon with a turret made of stone ashlars at each angle.