Who Built the Erdstalls and Why?

Medieval bug-out bunkers or places for secret cult ceremonies - no one can say for sure.

Entrance to an erdstall in the Rohrwald region of lower Austria. It is locally known as a Schwedischhöhle (‘Swedish cave’ or ‘Swedish hole’) because people hid in them in the 17th century during the Swedish Wars, part of what became known as the Thirty Years’ War. Photo credit: Naoag - own work, republished via Wikimedia Commons and Creative Commons license. CC BY-SA 4.0,

It is a mystery that has puzzled European historians for hundreds of years and is still hotly debated. Who constructed the thousands of narrow, empty, underground tunnel networks scattered all over Europe?

Known as ‘Erdstalls’ — the etymology is from the Middle High German erde for ‘earth’ and either stelle for ‘place’ or stollen (mineshaft) — they are most heavily concentrated in southern Germany and Austria. (There are more than 700 in Bavaria alone.) But they have also been documented in Hungary, Spain, France, Ireland and Scotland.

I first heard about them from this article in the newsletter, weird medieval guys.

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