Between 1911 and 1916, the Rove Tunnel was built to link the Marseille Harbor to the Rhone River. But it wasn’t until 1926, after twenty years of work and a World War, that the tunnel was finally opened for use, surviving a little under 40 years before collapsing in 1963.

The longest canal tunnel in the world, the Rove Tunnel passes through Berre Lake (adjacent to the Mediterranean to the west of Marseille) and Martigues (a commune in the southeastern part of France, to the northwest of Marseille), and stretches about 4.5 miles in length and 72 feet in width, which, before it was closed to public use, enabled about two ships to cross inside.

Although it has been abandoned for years, a project has been launched to bring this tunnel back to life by using it as a salty water supply for the Berre Lake, which is slowly drying.