Twilight at a Peruvian salt mine

Did you know this is what salt mines look like?

A salt mine is an operation involved in the extraction of salt. Areas known for their salt mines include Khewra in Pakistan, Tuzla in Bosnia, Wieliczka in Poland, Salzkammergut in Austria, Rheinberg in Germany, Slănic in Romania, Provadiya in Bulgaria, Avery Island in Louisiana, the Wich towns of Cheshire and Worcestershire, United Kingdom, and Torrevieja in Alicante, Spain.
Prior to the advent of the internal combustion engine and earth moving equipment, mining salt was one of the most expensive and dangerous of operations. While salt is now plentiful, in the ancient and medieval world, salt was difficult to come by, and salt mining was often done by slave or prison labor. In ancient Rome, salt on the table was a mark of a rich patron (and those who sat nearer the host were above the salt, and those less favored were "below the salt"). Roman prisoners were given the task of salt mining, and life expectancy among those so sentenced was not great.