I know, I've been there twice - first something like 20 years and second - couple of months ago.
It's really great.
Here are some pictures from Wieliczka salt mine:
The Casimir the Great Chamber
The Erazm Baracz Chamber
John Paul II - The Chapel of Saint Kinga
The Chapel of Saint Kinga
The Chapel of Saint Kinga
The Michalowice Chamber
The Warsaw Chamber
The Chapel of St. Anthony
The Weimar Chamber
The Spalona Chamber
Crystal cave
The Witold Budryk Chamber