It is said that St. Kinga, daughter of King Béla IV of Hungary, brought salt to Poland as her dowry. The story is long, but she basically was to marry the Polish Prince Bolesław Wstydliwy (Boleslaw the Chaste) and didn't want jewels or gold as a dowry since she said Poland was a rich country. She decided salt would be most appreciated by the Poles, so after her father brought her to a Hungarian salt mine but said he didn't know how to get all the salt to Poland, she prayed to God for advice and threw her engagement ring down a shaft. After marrying the prince, they were surveying his principality when she ordered her servants to dig in the ground. They hit rock, a piece of which they broke off and gave to her. It was salt, and inside of it was her engagement ring. Thus began the very rich Wieliczka Salt Mine.

I dislike flash, but there was absolutely no choice in this cavern as well as a couple of other places.