Sala Silvermine in Sweden attracts hundreds of visitors each year to view its vast caverns and beautiful underground lakes.
The Mine has it's own standard (above ground) hostel plus one 'mining' suite 155m underground.
There is plenty of cave accommodation in Cappadocia, but the pick of the bunch is this stylish boutique hotel.
There are five individually designed rooms: doubles cost from £105 per night, including breakfast.
Hotel Sant'Angelo - in the southern Italian town of Matera - features sixteen “historic dwellings” set amid a Unesco World Heritage site: doubles from £140 a night, including breakfast.
The Laleh Kandovan International Rocky Hotel, Iran
Located on the edge of the mountain village of Kandovan, 27 miles south of the city of Tabriz, the Laleh Kandovan has 10 rooms, with another 30 planned, and a large restaurant.
All the rooms have underfloor heating and some have whirlpool baths. There are Persian rugs on the floor and the walls have recessed lighting. The decor is stylishly minimalist, using plenty of tiles and letting the rough rock sides do the talking.
Kokopelli's Cave, USA
Located north of Farmington, New Mexico, close to the Mesa Verde National Park, guests at Kokopelli's Cave can enjoy views over four American states.
The Cave Resort offers eleven one- and two-bedroom cottages built into the limestone cliffs off Negril, on Jamaica's west coast.
Rooms feature bold, bright designs with large beds, louvered windows, handcrafted furnishings and original artwork.
Les Hautes Roches, Loire Valley, France
Part of this 18th-century manor house is cut into the rock face of low cliffs overlooking the banks of the Loire near Tours.
A Relais & Châteaux hotel, it has 15 rooms; doubles from £142 a night.
One of a number of hotels in the Cappadocia region of Turkey, Gamirasu is located in a restored Byzantine monastic retreat in Ayvali Village near Urgup.
The hotel is a combination of seven houses, converted into 25 rooms - each varying in size and shape.
Also found in Cappadocia, Elkep Evi offers cave rooms with modern facilities on a hill overlooking the town of Urgup.
Alexander’s Boutique Hotel, Santorini, Greece
Located on the top of a caldera, with views of the Aegean, Alexander's offers luxurious accomodation in a picture-perfect setting.
There are seven “cave villas” (from £185 a night for two with continental breakfast) and nine cave houses (from £114 for a house sleeping two people).
