Underground tunnels from the nineteenth century where kaolinic sandstone was mined. The total length is about one kilometre.
The only way in is through a recently carved exploratory adit. Recently means about 15 years ago. Even so, the walls are already covered in corrosion and mold.
This is kind of how I visualize cancer.
I didn't stick around long. And after a 150 metres, the adit joins the old mine tunnels.
Although they look a bit claustrophobic in photos, it's not that bad in person. Most of the corridors in this section are tall and wide enough for an adult to walk through. Only around the original entrance to the shafts do the tunnels have very low ceilings in places, and here and there you have to walk sideways.
Occasionally, the tunnels extend into larger chambers, which then lead off into virtually every direction.
It's a bit disorienting at first but after a while you remember the landmarks. We had the whole area mapped out in our head in less than an hour during our exploration.
It is common for a tunnel to split within a few metres into three branches, each of which splits into three more, but two of which lead to where you came from.
It is very rare to find remains of human activity underground that can be classified as anything other than garbage. And there's plenty of rubbish in some places, like old beer cans. This tin cup is clearly not from the 19th century, but at least it adds more atmosphere than empty bottles of cheap vodka.
The underground has a somewhat uncertain future ahead of it. A part of it was already completely filled in with concrete years ago, when the apartment building was being built on the surface above the tunnels. City Hall can't decide which part of the city the underground actually legally belongs to. And the tunnels themselves aren't that stable considering the surface activity. For example, the next phase of housing construction could very well result in the collapse of part or all of the system.
So I'm glad I got underground at a time when it's humanly possible. It's possible that this window is quite short.