Ouvrage Sapey, Military fortification in Modane, France.

Ouvrage Sapey is a military fortification standing at 1,740 meters (5,710 feet) on a mountain summit in the Alps. The complex spreads across the high terrain with five combat blocks and one entrance block built from reinforced concrete.

The Séré de Rivières fort was built between 1884 and 1892, initially in masonry, then reinforced with concrete and rock-cut galleries from 1913 to 1916. In the 1930s it became the Maginot ouvrage du Sapey, whose 75 mm guns fired 2,409 rounds on Italian troops in June 1940. Italian forces occupied it after the armistice, German troops took over in 1943, and it was recaptured on 13 September 1944.

The site is a military property of the commune of Modane and access is forbidden. Its name comes from the Sapey summit, where a redoubt armed with ten de Bange 120 mm guns stood. The ensemble includes a barracks built in 1898 with an underground shelter for 500 men.

Access to the ouvrage, the fort and the redoubt is forbidden; the site is abandoned and belongs to the commune of Modane. The position lies about 1,600 metres west of Modane, above the Arc valley, and was once reached by an aerial tram built in 1908 that also linked it to Fort du Replaton.

The 1908 aerial tramway linked Sapey to Fort du Replaton down the slope, carrying men and supplies between the two positions. It was destroyed in 1944, during the fighting that retook the site on 13 September, and was not rebuilt.