It is clear, at any rate, that they were built by professionals. They dug the tunnels in a kneeling position, using wedge-shaped tools held with both hands. Every few meters, they chiseled cavities into the walls for their oil lamps. They dug the longer passageways in serpentine form to reduce the pressure from the surrounding earth. Supporting planks were not used.
Around the year 1200, the underground labyrinths were filled in and the entrances blocked with rubble. The rubble contained ceramics clearly attributable to the Gothic period.
The confusion over the tunnels is hardly surprising. 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.
The legendary Kilian, born in Ireland around 640 A.D., preached in the southern German city of Würzburg. According to a hagiography, angry natives killed him and buried him in a stable. St. Gall (died 640 A.D.) made it as far as Lake Constance.
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.
Were the galleries temples for the superstitious?
Hiding from Bandits
Not everyone finds these spiritual interpretations convincing. Josef Weichenberger can only shake his head when he hears them. He is talking himself into a rage as he speeds from the Bavarian city of Passau toward the Waldviertel region in Lower Austria. "The cult theories are completely erroneous."
Then he offers his interpretation: "The Erdstall galleries were simply hiding places."
Weichenberger's opinion carries some weight. An archivist by profession, he has been crawling through the labyrinths for the last 34 years. He also runs an alarm center from his office. When construction workers report the discovery of an Erdstall, he rushes to the site to document it with a compass and a measuring tape.
For this mole of a man, no tunnel is too narrow and no passageway too moist or dirty.
According to Weichenberger, the galleries in his native Austria were built during the "medieval clearing period" in the 11th century. At the time, settlers from Bavaria traveled down the Danube to cultivate land in the east.
Armed with hatchets, they cut swaths into the wilderness. It was not an entirely safe undertaking. Magyars flooded into the area around 1042. Around 1700, the Hungarian rebels known as Kurucs, with the backing of the Ottoman Turks, ransacked the countryside.