Fort de Roppe built
1875 CE.
Shown on the map at 47.680°, 6.900°.
Fort de Roppe, also known as Fort Ney, was built between 1875 and 1877. It is part of the second ring of fortifications around the city of Belfort in northeastern France. This set of forts was built as part of the Séré de Rivières system and incorporated improvements to deal with the improvement in efficacy of artillery in the late 19th century.
Text from the Wikipedia article Fort de Roppe, licensed CC BY-SA 4.0.