What is an erdstall?

An erdstall is a type of tunnel found across Europe. They are of unknown origin but are believed to date from the Middle Ages. A variety of purposes have been theorized, including that they were used as escape routes or hiding places, but the most prominent theory is that they served a religious or spiritual purpose.

There are very few historic references – a document from 1449 names the area above the tunnels as 'auf den erdstelln' ("on the ground"). Although the modern term uses -stall (stable, shed), this stems from the word stelle (spot, location - cognate to the English "stead"), and is combined with 'erde' (soil, ground - cognate to the English "earth"). The German 'stollen' ("tunnel in mining") has the same origin.

Erdstall tunnels have only one narrow concealed entry point, with no second exit tunnel as with an escape tunnel system. Some tunnel systems feature loop tunnels at the end of a tunnel. Most tunnel systems are no longer than 50 metres (160 ft).

There is almost no archaeological material to be found in the tunnels, although erdstall tunnels exist in abundance in Central Europe, with over 700 in Bavaria alone. This makes it highly unlikely that they were ever used as dwellings, such as a hiding place in times of war.