Čertovy mlýny, Rock formation in Bukovec, Czech Republic

Čertovy mlýny is a rock formation that emerges near the peak of Girová mountain, consisting of several natural stone structures with numerous cracks and fissures. The rocks form a complex pattern of caves and narrow passages that shape the landscape of this mountain region.

The sandstone formation was shaped by the continental Nordic glacier, which affected the area twice during the Ice Age. After the ice retreated, water-swollen clay soils between the sandstones became slippery, triggering landslides of soil and sandstone that opened the fissures, cavities and caves typical of pseudokarst. Speleologists have explored several caves, most now filled in.

Legends tie the site to outlaws who hid here in the time of Juraj Jánošík, to devils who wanted to grind disobedient people on the stone mills, and to witches who gathered at the rocks. The Czech name Čertovy mlýny means "Devil's Mills".

The rocks lie just southwest below the summit of Girová (840 m) near the Girová mountain lodge in Bukovec. They are reachable year-round only along an unmarked forest path, so orient yourself by the summit and the lodge rather than by trail blazes. Only one cave, 9 m long, is easily accessible to ordinary visitors; the others are mostly filled in.

The sandstone here was shaped by the continental Nordic glacier, which affected the site about twice during the Ice Age. After it retreated, water-swollen clay soils between the sandstone turned slippery and triggered landslides of soil and rock, producing the fissures, cavities and caves typical of pseudokarst.