Entering Luxembourg’s Hohllay Cave, one might be forgiven for thinking that it was once home to an order of druids or some other  ancient sect thanks to strange marking covering the cave walls. But really it’s just mining scars.

Located in a forested area of the Little Switzerland section of Luxembourg, the Hohllay Cave has been the site of mining since medieval times. Also known as The Hollow Cave or the Breechkaul Cave, the low-ceilinged cavern was created when the rock was used to create circular millstones. This mining lasted into the 19th century, leaving the entire cave marked in eerie, scalloped designs from the cutting. There are also pillars that were left as supports, giving the cave a somewhat cathedral feel.

It also acts as a natural amphitheater and concerts are now held there as weather permits. The cave is also a popular hiking destination. 

There are plenty of caves with actual petroglyphs and ancient designs for archaeologists to pore over. But it took some marks from simple industry to create the beauty and mystery of the Hohllay Cave.