Salt of the Alps: ancient Austrian mine holds Bronze Age secrets All mines need regular reinforcement against collapse, and Hallstatt, the world's oldest salt mine perched in the Austrian Alps, is no exception. But Hallstatt isn't like other mines. Exploited for 7,000 years, the mine has yielded not only a steady supply of salt but also archaeological discoveries attesting to the existence of a rich civilisation dating back to the early part of the first millennium BC.