Peek into a cave of giant, glimmering crystals.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

This life-size monument honors the legacy of a famous literary feline.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

This natural wonder drops 16 stories straight down through rare flora and streaming waterfalls.

Ruins of a historic medical facility sits eerily by the water.

Underground tunnels remain beneath this abandoned mental asylum.

An unusual library of dead things at the Rhode Island School of Design.

The exact whereabouts of this surreal cabinet of curiosities are rarely the same place twice.

The abandoned husk of a mental institution that failed to save a Jazz Age icon still sits nearly unchanged.

Quirky castle designed by the American actor best known for portraying Sherlock Holmes on stage.

An abandoned Victorian-era mill in the middle of modern Manchester.

The intriguing personal collection of a professional demon-chaser.

An overgrown and abandoned tuberculosis ward resides in the midst of a quaint modern neighborhood.

The remnants of a 19th-century ironmaking complex hidden in the woods of Connecticut.

The walkable ruins of an 19th century hotel, destroyed in a horse cremation gone wrong.