Mont-Dauphin is a commune in the Hautes-Alpes department in southeastern France. At the confluence of Durance and Guil rivers, o…Mont-Dauphin is a commune in the Hautes-Alpes department in southeastern France. At the confluence of Durance and Guil rivers, overlooking the impressive canyon of the latter flowing down from Queyras valleys, Mont-Dauphin is one of the many places fortified by Vauban in the second half of the 17th century.