In 1679, when Vauban ordered the fortification of Villefranche, he deemed it necessary to protect the site by building a fort on the mountain. The latter was remodelled in the 19C and equipped with a pink Conflent marble staircase of "one thousand" steps (in fact only 734), linking the fort to the town. The fortifications, composed of three successive outer walls designed to espouse the steep terrain, served as a prison under Louis XIV in the Poison Affair.