Why are there secret ancient underground chambers and tunnels connecting old farmhouses, churches and even cemeteries and forests in Bavaria, Germany? Nobody knows - even the experts are baffled:
The vaults could not have served a practical purpose, as dwellings or to store food, for example, if only because the tunnels are so inconveniently narrow in places. Besides, some fill up with water in the winter. Also, the lack of evidence of feces indicates that they were not used to house livestock.
There is not a single written record of the construction of an Erdstall dating from the medieval period. "The tunnels were completely hushed up," says Ahlborn.
Archeologists have also been surprised to find that the tunnels are almost completely empty and appear to be swept clean, as if they were abodes for the spirits. One gallery contained an iron plowshare, while heavy millstones were found in three others. Virtually nothing else has turned up in the vaults.
There's one thing they do know: there are hundreds of these secret underground mazes all over Germany and Austria.