A substantial ensemble of statues and decorative elements sculpted into the rock salt has been preserved in both mines, along with an ensemble of tools and machinery. An underground tourist route has ...

In the early 19th century, Europeans on the hunt for saltpeter ... he wasn't impressed with its saltpeter production. Companies were mining saltpeter in the region by the early 1800s.

The 2016 documentary The Mine Wars examines two notions of ... that inspired the early labor unions in the late 19th and early 20th century were actually much broader than that.