Wieliczka Salt Mine (UNESCO Heritage Site)
The mine has been built in the 13th century and it produced salt continuously until 2007 - it is also one of the oldest salt mines in the world. I always knew it was there but from Łódź to Kraków it's over 3h ride and I never seemed to find the time. Finally when I was almost 30 my parents and I decided on a visit. They only saw it once back in high school.
It was incredible! You start the tour walking down the stairs, in the end you end up about 135m below the surface. You walk through many different rooms, all corridors are carved in salt. Throughout the centuries miners have been sculpting in salt and you can admire their achievements in the halls. Even all the chandeliers are made out of salt.
One of the most amazing rooms is the so called "Cathedral" the Chapel of the Saint Kinga - Hungarian noblewoman who married a Polish prince and is considered the patron saint of miners. It is a huge hall where on the walls instead of normal paintings you have them carved into the walls. One of them being the "Last Supper"!
Apart from the great attention to detail what touched me most was the heart that the miners have poured into their work. Not just getting the salt but taking the time to turn it into works of art.