Built between 1668 and 1711, Besançon Citadel, considered one of the finest citadels in the country, stretches over 11ha. The current shape of this fortress that dominates the Doubs is down to Vauban, who altered it in 1674. Three successive bastions, three esplanades, ramparts with a covered walkway, watchtowers, various exhibitions and instructive museums make this a natural and historical site of great interest, classified as a UNESCO World Heritage Site.