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. The archaeological evidence is so slim that even age determination is difficult. Coal from a fire pit at has been dated between 1030 and 1210. Coal from a heading in has been dated between the late 10th and mid-11th century. A slip passage at has been enhanced with stones to make it narrower with the stone additions dated to between 1034 and 1268. Coal from was dated 950 to 1050, coal from was dated to 950 to 1160. Ceramics found in St. Agatha have been dated to the 12th century, which seems to be the latest date of usage. Museums Most erdstall sites are too narrow to be usable for general tourism. A bigger walkable site is the Erdstall Ratgöbluckn in Perg (Upper Austria) that is open to the public as part of the local museum of Perg. The Erdstall am Kapellenberg in Großkrut (Lower Austria) was opened in 2007 to visitors of the Erdstallmuseum Althöflein. See also – Hindus believe that crawling through the tunnel will wash away all of one’s sins and thus attain freedom from rebirth. – souterrain structures in Cornwall of unknown usage. References External links – study group for erdstall tunnels – journal report on erdstall tunnels – "Unser Erdstall" - detailed report on the erdstall in Gaweinsteil (found in 2007) – more than 700 underground passages and menhirs Tunnels Subterranea (geography) Open problems