Forte del Gran Serin, Military fort in Meana di Susa, Italy.

Forte del Gran Serin, also called Batteria del Gran Serin, is a ruined fortification stretched lengthwise across the 2,600-metre contour along the Assietta road near the Colle dell'Assietta. It holds artillery emplacements, barracks with stables for up to 850 soldiers, and a powder magazine, all enclosed by a long wall of which part is now missing.

Forte del Gran Serin was built towards the end of the 19th century as part of the defences of Italy's north-western alpine border, along the Assietta road near the Colle dell'Assietta. Its artillery positions, barracks and powder magazine were laid out to sweep the ridge from the top of Assietta to Monte Gran Costa. The structure is now in ruins and part of its long protective wall is missing.

The fort's name comes from the Gran Serin ridge it occupies; its long wall, artillery emplacements and stables for up to 850 soldiers show how a late-19th-century Alpine battery was organised. Visitors today walk the ruined ramparts and see where the wall has collapsed.

Access is by unpaved road open from June to October, with vehicle traffic allowed on Wednesdays and Saturdays during summer months. Arrive early and bring suitable gear, as mountain weather can change quickly at this high elevation.

The fort's position allowed its artillery to cover multiple Alpine valleys at once, from nearby peaks down to lower passes. This strategic placement made it one of the most commanding defensive positions in the region.