Fort du Replaton, Military fort in Modane, France

Fort du Replaton stands at 1,210 metres above Modane, a Séré de Rivières fortification of grey-brown stone built into the rocky slope above the Arc valley. A long masonry wall runs across the hillside, with a low rounded structure on the left, flat-topped blocks and a taller block in the centre, and two casemates with sloped upper corners to the right. A perimeter wall and surface barracks distinguish it from later Maginot works.

The fort was built between 1884 and 1892 as part of the Séré de Rivières fortification system using the most advanced military architecture of that period. It was created to protect the new rail connection to Italy, which held strategic importance for France.

The fort's name comes from the Replaton plateau above Modane's station district. Its layout, with a perimeter wall and surface barracks rather than buried galleries, follows the Séré de Rivières system and was later compared to Fort Saint Michel near Toul. The smaller Redoute du Replaton, at the plateau's eastern end, held a single 95mm gun.

The fort is private property of the Association de la Traversée des Alpes and its interior is closed to the public; the masonry and casemates can be seen from outside. It stands at 1,210 m above the Arc and Modane, reached on foot from the town, and the aerial tramway that once linked it to Modane and on to Fort du Sapey no longer carries visitors.

The fort's layout anticipated later Maginot Line designs, with a communicating gallery cut into the rock behind the position holding two 95mm and two 155mm guns. It resembles Fort Saint Michel near Toul, and unlike a Maginot work it was enclosed by a perimeter wall with surface barracks. Construction cost about 2 million francs.