One of the features that unites us with other societies in the past is our ability to catalog and map. Today, without fear of being mistaken, we can say that almost every corner of the planet has been mapped, divided and described, even according to periods and changes occurring in each region. Logical. Maps show the history of our world. But an unsolved mystery remains underground: the Erdstall tunnels.

First there was one, then thousands. The first of these strange tunnels were found in Bavaria and Austria in the 19th century, when they began to attract the attention of archaeologists and explorers. Today, more than two thousand individuals are seen across Europe, reaching areas such as France and England. As we will see below, almost all of them have things in common, but no one knows what their origin and use are. So far.

Features. The Erdstall tunnels are extremely narrow, several meters long, and are connected by small gaps called “schlupfs”, forcing those passing through them to pass through them (barely enough for a single person). The Schlupfs would theoretically serve as transition points between parts of the passes excavated at higher or lower elevations.

Another oddity is that they often have an entrance and exit hidden in the traces of ancient settlements, or even hidden in nature, which clearly suggests deliberate design. More data. It is carved into a smooth oval shape, aligned either vertically or horizontally. Its dating is generally estimated to be in the Middle Ages, in the 12th century, but these are assumptions due to the lack of archaeological or historical artifacts mentioning such structures or their construction themselves.

The entrance of the Ratgöbluckn Erdstall in Perg, Austria, open to tourists since 2002 and with electric lights

Theories. In 2011, Der Spiegel sparked interest in the tunnels by suggesting several possible meanings. One theory is that they were used for storage, but the narrow slip passages and the fact that many are located below the waterline and occasionally fill with water make this appear largely impractical.

Another popular explanation, advocated by Erdstall researcher Josef Weichenberger, was that the tunnels were important hiding places for farmers who wanted to avoid marauding tribes. According to the second theory, the outlets separating the rooms were placed to retain oxygen in each section. However, these seemed unlikely to be a defence, given their apparent claustrophobic nature.

“Other” hypotheses. Of course, folklore has also revived these mysterious tunnels from time to time. In Austria, where they now number 500, local folklore suggests they were built by elves for sacred or spiritual “works,” and of course theories about beings from other planets also abound.

Piece. The truth is that groups such as the Erdstall Research Working Group have been emerging for some time. Behind this name is a team of researchers who have been working on tunnels for years and looking for answers with techniques such as 3D topography. They share their findings at meetings every year.

But the biggest progress has come very recently. Raimund Edlinger, a roboticist and cave explorer since childhood, joined an expedition to map the mysterious Erdstall tunnels in Austria. Because the tunnels are so difficult to examine, Edlinger and his colleague Kurt Niel used a handheld device equipped with cameras and sensors to create 3D images of the structures.

Revelation and hypothesis. With this method, they say they have deciphered interesting details such as possible doors and barricade systems to protect the tunnels from intruders; This suggests something that has already been theorized: a defensive use, at least in certain situations. Through these scans, researchers discovered that the tunnels were likely dug from a central point and that materials were removed before the chambers were connected to each other.

Another researcher, in this case Luc Stevens, suggests that they may have served as temporary storage or hiding places rather than a ritual or defensive purpose. Even so, one thing seems clear: it is fascinating to observe how such an architectural challenge was solved with such limited tools in ancient times. Both Niel and Stevens continue to investigate the tunnels to find more answers. Through this latest research, they hope to learn more about the lives of those who built the tunnels and their possible uses.

A fascinating and unknown part of European history.

Image | Jawei, Josef Weichenberger, Pfeifferfranz

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