Danish Archaeologists excavating under a train station in Copenhagen, Denmark have discovered a mysterious and completely secret tunnel dug beneath the station. Dug 19 feet below Østerport Station, the narrow tunnel is believed to have been some sort of escape route, but researchers have no idea who built the tunnel or for what purpose. Due to its proximity to historic military fortifications of the city, the tunnel was initially assumed to have been a leftover from one of the many armed conflicts fought over Copenhagen. Analysis of the wood used to build the tunnel, however, puts the tunnel's construction somewhere in the late 1800s, far removed from any known historical reason for its construction.
According to Andreas Flensborg, an archaeologist with the Museum of Copenhagen, everything about the tunnel is mysterious:
“The tunnel is seemingly cut off by the rampart at Østerport Station, but the other end continues under Østbanegade. We don’t know if it turns or where it ends. It’s a mystery.
When you find such a tunnel, it gives a rush to the body. What does that mean? You ask yourself how extensive these systems are—and are there many more tunnels?"
Like many cities in Europe, Copenhagen has seen its fair share of conflict and has had many iterations of military fortifications constructed throughout its history. Initially, archaeologists believed that the tunnel was a remnant of a two-year siege on Copenhagen by the Swedish army in the 17th century. The tunnel was found in close proximity to other 17th century fortifications but analysis of the wood used in the tunnel's construction dates it to 1874, which is strange.
Hanna Dahlström of the Museum of Copenhagen says that the tunnel's construction methods are similar to those used on the Western Front of World War 1 roughly 36 years later. She does say that this tunnel may have been initially constructed much earlier and then repurposed and repaired. Although the purpose is still not clear. The Museum of Copenhagen says that no other tunnels of its nature have been found in the city and it does not appear on a single map. She says:
"Maybe it has been repaired, which is why there is younger woodwork. We are investigating it now. We had expected it to be an escape tunnel [from the] 17th century.
It wasn't something we expected to encounter. That way, it's big and exciting. It's not often you find something so unexpected. We also don't really know what function it has had, and that just makes it even more exciting.
It's easy to forget just how much history has occurred in old European cities like Copenhagen but was never recorded. The original purpose of this tunnel might never be known, but it's fair to say that there are probably many such mysterious construction projects in cities all over the world. How much history do we walk on top of every day without ever knowing it's there?