The huge dome of salt at the town of Cardona in Catalunya has been exploited for 4,000 years. Industrial-scale mining began in the early twentieth century for potassium chloride, used in making fertilisers. The Mina Nieves de Cardona expanded in the 1920s under the Unión Española de Explosivos. Before it closed in 1990 it employed over 500 people and extended to a depth of 1,300 m. It is now the Salt Mountain Cultural Park. Displays on the surface explain the importance of salt, the history of the mine and the park’s unusual geology and natural history. Visitors see the surface buildings, including the steel headgear for the Maria Teresa shaft and the engine house with an electric winding engine of the 1920s. A choice of standard or ‘theatrical’ guided tours take people 86 m underground to see mining tunnels, salt formations and caverns.