Peek into a cave of giant, glimmering crystals.

A road that winds through this natural cave is the only way to access the small, appropriately-named village of Cuevas.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

A gargantuan crystal kingdom.

In Rickwood Caverns, visitors can travel hundreds of feet underground and see beautiful formations unique to the region.

At this gas station in the middle of the desert, a convenience store has been carved directly into the rock.

The natural hot spring that was integral to the creation of Canada's first national park.

These 400 million-year-old caves feature honeycomb limestone formations.

400 million years of erosion shaped these fascinating seaside caves, which made an appearance on 'Game of Thrones.'

An ancient cave system in Tennessee’s Appalachian foothills converted to a 1,200-person music venue.

A massive cave once a secret military base is now home to thousands of bats.

This cave was once thought to be a hiding place for the devil.

The largest cave on the island of Menorca was likely the site of Iron Age rites and rituals.

Take an underground boat ride through a former hydraulic raceway that was built in the late 19th century.

The ceiling of this cavern is dripping with multicolored marble stalactites.

Ancient rock-hewn town that witnessed key events of Georgian history.

Live a night as a Byzantine King, with a minibar and private jacuzzi.

While not Turkey's deepest underground city, this subterranean redoubt is the largest.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

Eight rare Corvettes are swallowed up by a sinkhole in Kentucky's National Corvette Museum.

The world's longest known cave system.

Though difficult to access, this stunning cave has a place in Scotland's poetic history.

This dramatic landscape hidden on the Isle of Skye looks as though you've stepped into the magical realm.

These fantastically named natural pools look like something out of a Scottish myth.