United Kingdom's Go Below offers adventure-packed cave tours in North Wales. But what made the company world famous is the unique accommodation set 1,375 feet (419 meters) below the ground level in an abandoned Victorian slate mine. Snowdonia's disused slate (a type of rock commonly used in construction) mines are …

The salt mine in Wieliczka is a significant tourist attraction and is visited yearly by over a million people. Operation of the mine ceased in 1996, after over 750 years of continuous operation. It's one of Europe's oldest salt mines and consists of a labyrinth of tunnels of over 124 …

Lounge on your luxury leather chair underneath a delicate chandelier that hangs from the roof of a room that has been tunneled out of a pure rock, 509 feet (155 meters) below the surface. As if you were Gollum from Lord of the Rings. Except for the massively wealthy and …

A former limestone quarry, this privately owned boutique hotel has been a labor of love for the family that owns it. The idea was to make the structure as simple as possible so as not to detract from the stunning surroundings of Gotland, Sweden’s largest island and home to Visby …