The Wieliczka Salt Mine, located in the town of Wieliczka, is within Poland's Kraków metropolitan area. It had been until 2007 in continuous operation, producing table salt, since the 13th century. Active mining was discontinued in 1996 due to low salt prices and mine flooding.
The mine remains a major tourist attraction which attracts around 1.2 million people to the mine each year. You can see why, the place looks like a Quake level or a Bond villan's secret lair and almost every chamber is a fantastic photo opportunity.
Here are some VR images from the mine's official site Virtual tour.

