The Wieliczka Salt Mine near Krakow is a marvel of human ingenuity and natural beauty, offering visitors a journey into an underground world of lakes, chapels, and chandeliers-all made of salt.

In the heart of the Austrian Alps next to Salzburg, the Hallein Salt Mine conceals a world that was fashioned for 2,000 years by the "white gold" that is salt. Kitted out with a coverall ...