Rove Tunnel
The 156th longest tunnel in the world
The Rove Tunnel (Tunnel du Rove) is a currently out-of-use canal tunnel in Southern France that connected the 16th arrondissement of Marseille to the Étang de Berre in the Bouches-du-Rhône department from 1927 to 1963. It allowed for waterway transport avoiding the Mediterranean Sea towards the Rhône within the larger Canal de Marseille au Rhône. With a length of 7,120 metres (23, 360 ft) it was a major work of civil engineering; it remains the longest canal tunnel in the world.
Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).