More than 1,200 "Erdstall" tunnel complexes are known to exist in Germany and Austria, "and no one knows why," reports Matthias Schulz:
Some believe that they were used as dungeons for criminals, while others see them as places of healing, where the sick could cast off their afflictions. Still others speculate that they were used by druids. As a result of the international cooperation of the Erdstall working group, new clues have come to light.
The galleries are also concentrated in parts of Ireland and Scotland, and there are also clusters in central France. This distribution bears intriguing parallels to the routes of the Irish-Scottish traveling monks who, coming from the Celtic north in the 6th century, traveled across the continent as missionaries. The tattooed monks made the passage to the continent from the islands, carrying long staffs and wearing coarse habits. … Ahlborn speculates that these early Christian missionaries also brought along heathen ideas, the remnants of Druid scholarship or special Celtic concepts of the afterlife, which led to the construction of the subterranean galleries.
Perhaps the tunnels were also prisons for demons, evil dwarves and the undead. Some galleries contain traces of building stones and remnants of doors or locks. A sandstone relief was found in an Erdstall at Bösenreutin near the town of Lindau on Lake Constance. It depicts a goblin with a tail attached to its rump.
(Image: Erdstall galleries in Austria courtesy of this site.)
The Dish 