The oldest arboretum on the Dalmatian coast doubles as the gardens of Kings Landing in "Game of Thrones."

Large, airy hallways hide within an impenetrable fortress that beckons urban explorers.

Legend has it fairies gathered at the site of this medieval castle.

The complex has been abandoned since the Croatian War of Independence, barring a stint as a set for 'Game of Thrones.'

These pools have been abandoned for over 20 years.

A historic London cemetery now serves as a nature park incorporating gravestones & memorial statues.

The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

The Natural History Museum that time forgot.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

This elaborately decorated, fairytale-like Romanian royal palace is one of the most striking castles in Europe.

This fairy-tale castle would make Dracula (who is said to have been imprisoned there) jealous.

This massive underground salt mine now holds a sci-fi theme park in its depths.

Moss and stone turn this waterfall into an otherworldly liquid veil.

19th century museum with an eclectic mix of curiosities, from Egyptian artifacts to items on archery history to the skull of the world's oldest horse.

A Victorian Gothic masterpiece housing a world-class collection of rare books and manuscripts.

Stumbling upon this whimsical wooded garden is like stepping into an enchanted forest full of philosophical musings.

A dilapidated psychiatric facility on the outskirts of Milan where electroconvulsive therapy was developed and Napoleon once lived.

An abandoned Roman salami factory has found new life as an art space home to 200 squatters.

The Roman Emperor's lost summer home and grotto full of enormous sculptures sit along the Italian seashore.

A domed disco abandoned since the '70s now attracts artists and explorers under its unique roof.

Crumbling ruins of the thermal baths that once attracted royals and aristocrats from throughout Europe.

The abandoned "Ghost Mansion" was left to decay in the mountains of Northern Italy.

This real life asylum of horrors is now an abandoned ruin that hides the unbreakable code to one patient's insanity.

The astonishing collection of an infamous criminologist.