The secret medieval tunnels that we still don't understand

Summary

Around 2,000 strange tunnels have been found around central Europe. These aren’t like the well-known catacombs of Paris or Rome. Known as the erdstall, these passages are extremely narrow, never more than two feet (60 centimetres) wide nor high enough for an adult to walk in, and sometimes the passages become seemingly impossibly narrow, as small as 16 inches (40 centimetres) in diameter. Determining their age and purpose is made difficult by the fact that almost no archaeological evidence has been found inside any of them. A ploughshare was found in one, millstones in a couple others, but apart from that the erdstall are eerily empty. Carbon analyses of coal and pottery fragments found within point to construction dates of around 900 to 1200 AD, but no written records from the Middle Ages mention the erdstall’s existence. This clandestine treatment would have made sense had the erdstall been built as escape routes in case of invaders, but this can’t have been their purpose. They only ever have one entrance, usually located beneath the floor of a church or farmhouse, or simply under the flagstones of a town square. After an initial drop, the tunnels run for a few dozen metres, sometimes branching or dropping down to lower levels via narrow shafts. Often, the tight tunnels widen in the middle or toward the end into small chambers with rudimentary benches or shelves carved into the earth.No theory has yet been able to account for:The number and distribution of the erdstallThe similarities between the many erdstallThe inconvenience of accessing the erdstallThe secrecy with which these tunnels were built and guardedThe complete lack of artefacts found withinThe erdstall surely could not have been built with storage in mind, since their length and narrowness offer no advantages over a conventional and convenient cellar. And while three brave explorers in the 21st century once spent 48 hours in an erdstall, crawling to new sections whenever oxygen became scarce, it seems ...