thumb|Entry to the Ratgöbluckn erdstall at Perg, Austria – its passages are high enough for tourists to access (electric lights since 2002)
thumb|Entry to the Ratgöbluckn erdstall at Perg, Austria – its passages are high enough for tourists to access (electric lights since 2002)
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.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).