Large tunnel system in Dortmund

The Dortmund large tunnel system is located below the city of Dortmund at a depth of around 20 m. It comprises 4.8 km of deep tunnels and offered space for around 40,000 people. It extends roughly from Dortmund Central Station to Westpark . If it had been completed and connected with further tunnels, the entire system would have covered around 9 km. Some parts are filled today.