Once one of the largest mercury mines in the world.
Mercury was discovered there in 1497, and mining productions were taken over by the government in 1580.
According to legend, a bucket maker working in a local spring spotted a small amount of liquid mercury over 500 years ago. Idrija is one of the few places in the world where mercury occurs in both its elemental liquid state and as cinnabar (mercury sulfide) ore. The subterranean shaft mine entrance known as Anthony's Shaft (Antonijev rov) is used today for tours of the upper levels, complete with life-sized vignettes of workers over the ages. The lower levels, which reach to almost 400 meters below the surface and are no longer being actively mined, are currently being remediated.