Hallein Salt Mine

The Hallein Salt Mine, also known as Salzbergwerk Dürrnberg, is an underground salt mine located in the Dürrnberg plateau above Hallein, Austria. The mine has been worked for over 7,000 years since the time of the Celtic tribes and earlier. It helped ensure nearby Salzburg would become a powerful trading community. Since World War I, it has served as a mining museum, known for its long wooden slides between levels.

Source: Wikipedia