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 operated as a mining museum, known for its long wooden slides between levels, where the tourists are photographed and their speed recorded.

The Bavarian–Austrian Salt Treaty of 1829 is one of the oldest European treaties still in effect. It was signed by the Kingdom of Bavaria (now the Free State of Bavaria) and the Austrian Empire (now the Republic of Austria). It gave the Austrians the right to mine in Bavaria in exchange for wood. This treaty was necessary as the mine went through the border into Bavaria. (The Anglo-Portuguese Alliance of 1386 appears to be the oldest still in effect).