Inside, rough stone walls line passageways and rooms, reminding visitors that they are just as much in a castle as they are in the body of, essentially, a huge rock.

The scalloped rock walls suggest fast moving waters in this passage deep underground in Clearwater Cave, Sarawak, Malaysian Borneo. Clearwater Cave is the 8th longest in the world. Photograph by ...

The caves weren’t five-star accommodations with internal hydroelectric power plants and brick-lined walls–the kind sometimes imagined in the computer-generated images of the press.

The Marble Caves sit on the shores of a turquoise glacial lake in southern Chile. Light bounces off the water onto the walls, creating a magical, ever-changing display inside the caverns.

Well, if you've clicked on this story, you already know a little bit of what you're in for. But the cave house of Glenwood Springs is more than meets the eye, and we'll take you inside to show you ...

More than 57,000 years ago, a human traced their fingertips along the chalky wall of a French cave, leaving shallow, parallel furrows behind. But what species were they?

Tucked deep into Cappadocia’s iconic rock formations is a cave hotel unlike anything you’ve ever seen. It’s ancient on the outside but full-on luxury inside—with spa baths, stone-carved ...