Forts de l'Esseillon

Forts de l'Esseillon is a fortification system of five separate forts positioned along a rocky ridge at about 1500 m (4,900 ft) elevation in Savoie. They are spread across the natural rock formation and work together as an integrated defensive network.

The fortification system was built between 1817 and 1834 by the Kingdom of Piedmont-Sardinia to defend against potential French invasion through the Mont Cenis pass. Their construction reflected post-Napoleonic anxieties about mountain borders in this Alpine region.

The forts are named after members of the House of Savoy, connecting this mountain ridge to a royal past and territorial identity. The fortifications represent how military architecture shaped how people thought about borders and protection in this alpine region.

The forts are accessible on foot year-round, though the walking routes vary in difficulty and can take several hours depending on which ones you visit. Winter snow and ice can make conditions challenging, so sturdy footwear and good preparation are needed.

The Marie-Thérèse Redoubt now operates as an interpretation center displaying exhibitions about fortification design and military strategy. Visitors can learn how these mountain defenses were engineered and what made them effective against potential threats.