Kappelberg Tunnel
The 406th longest tunnel in the world
The Kappelberg Tunnel is a road tunnel on the Bundesstraße 14, located near the city of Stuttgart, Germany. Following failings identified by the European Tunnel Assessment Programme, the tunnel underwent a €12 million refurbishment programme, which resulted in a rating of "very good" in 2006.
Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).