The geographical location of Briançon has been the subject of much attention and covetousness throughout centuries, especially from 1690 at the end of the alliance between France and the Duchy of Savoy. Its strategic role was then asserted, pushing for the permanent occupation of the positions threatening Briançon. Vauban and his successors reinforced and developed the city's fortifications and secured its accesses by linking the defenses together. Such initiatives formed a line of defense that testifies to the evolution of French military architecture.