One of the most impressive fortifications I have even visited. Built when the art of warfare was changing and gunpowder and cannon were emerging on the battlefield. Fort de Salses is situated in the Catalan area of France. Built in the 15th Century by the Spaniards to guard the frontier against a French invasion. Recaptured by France in 1642 and always added to and changed to address the advances in defensive fortifications; never retaken again and remains to this day in French hands. A good example of the defensive architecture at the time are the round turrets. Round to deflect cannon balls. If you ever get the chance, do visit, well worth it. It really is huge and the guided tour is a must.