Kandovan Tunnel
The 373rd longest tunnel in the world
The Kandovan Tunnel, officially 11th Tunnel, is a major road tunnel on Chalus Road, Iran. The 1,883-metre (6, 178 ft) tunnel crosses Alborz, connecting Alborz province to Mazandaran province. It was completed in 1938 as one of the first tunnels in Iran in order to make the route from Tehran to Caspian Sea passable in harsh winter times.
Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).