Saturday, Aug 22, 2020, 9:29 am

By:Tony Williams

#5 Wielczka Salt Mine

This is in Poland and the size of it is absolutely mindblowing. The place was worked on from the 13th century with tons of salt being mined over the centuries and the result is that these mines now cover 186 miles in total, so you can imagine how long it would take you to explore it all.