Erdstall

An erdstall is a very old underground tunnel system that was used by people a long time ago. These tunnels are usually found in places like Europe and are sometimes hundreds of years old. People think that they were used for different things, like homes or hiding places, but no one really knows for sure. They are very long and narrow, and sometimes you have to crawl to get through them because they are so small. The tunnels are made out of stones or dirt, and they are underground to keep people safe from enemies or wild animals. Even though erdstalls are really cool and interesting, they are also very old and possibly dangerous places, so it's important to have a grown-up with you if you ever get to see one.