That’s what brought us to Sextantio Le Grotte della Civita, an 18-room albergo diffuso ("scattered hotel") built into centuries-old caves in the mountainside city of Matera in southern Italy.

Luxurious spa area inside Italy's new Aquatio Hotel and Spa, itself built inside a series of ancient natural caves. Modern-day view of the ancient Italian town of Matera.

Preservationists got obsessed. UNESCO named Matera a World Heritage Site in 1993, and then came the alberghi diffusi – hotels made of rehabbed dwellings scattered throughout the city.

From snow caves to tunnels, going underground has never been more luxurious. Here are the 13 of the best cave hotels to add to your travel bucket list.

Sextantio Le Grotte della Civita is an 18-room albergo diffuso ("scattered hotel") built in rock-hewn dwellings from the Paleolithic cave complexes of Matera, Italy, known as the Sassi.