Years ago I visited Slovakia, and my hosts took me on a daytrip to Krakow, Poland. We also stopped at the Wieliczka Salt Mines and took a tour. It was quite amazing, though a bit more touristy than I usually prefer. I did get to ride up a rickety mine elevator. That was an incredibly scary ride, and not at all touristy, so it more than made up for the rest.
Dariusz wrote about the legend of this mine. St. Kinga was in Hungary and was engaged to a Polish prince. She tossed the engagement ring in a salt mine in Hungary and when she reached Poland, she instructed a similar mine be dug. Sure enough, the workers in Poland found a salt nugget with Kinga's ring.
The room featured in this postcard is St. Kinga's Chapel. It is often used for large functions, like weddings. Quite a unique place for a party!