Unfortunately the vacation is now over. But I did come away with some nice photographs! We visited two Dutch cities – Arnhem and Maastricht. One of the places we visited in Maastricht was the caves of St. Pieter – the north caves to be exact. These caves were dug out to extract the limestone (or marl). At its largest it used to have 20,000 corridors and measured 230km. Now it measures about 80km.
Interestingly the first corridors were short enough that most adults would have to crouch to make their way through. As time went on and more limestone was needed, the floor itself was dug out, creating tall corridors that were easily 4-5 meters tall in some places. The guide also showed us ruts in the wall at some corners. The most efficient way to transport the limestone out was by cart and horse and horses tend to take the shortest way possible, which meant that they would push the wheels of the cart against the wall, creating the ruts.
The best part of the tour was when the tour guide asked us if we wanted to walk a bit of the caves in complete darkness. About 30 meters – this stretch had no turns on the left side for you to lose yourself, so all you had to do was keep your left hand on the wall and walk carefully/slowly. Note that this was an option – those who did not want to partake went on ahead with the lanterns and waited for us to arrive. It was incredible (and I humbly admit this was because it was in a controlled environment). I was nervous at a few points though!
Here are some photos of the drawings. Note that these were done in charcoal as that was the only medium that would not decay in this damp, cold environment (10c/50f year round).