Erdstall tunnels, Found across Europe

 

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Stretching across a sizable chunk of Europe, these tunnels are believed to date back to the Middle ages. With no records hinting at their use or reason of existence, it is widely speculated that this interconnected network of tunnels acted as a prison for demonic entities, and held a significant place amongst religious and spiritual connections. Others believe that they served as hideouts for robbers and convicts. The tunnels are very narrow and barely tall to walk through. A majority of the labyrinth being shrouded in darkness, only a part of it has been explored. Only these parts are open to the public on grounds of tourism.