A unique underground structure dating back to the 1st century BC.

A public park off the beaten path with a beautiful waterfall and 13th century Cistercian abbey.

This historic island prison holds one of the dungeons from the Count of Monte Cristo even though it is a work of fiction.

This collection of lurid religious statues tell the tales of a saint who stood down the devil.

The former home of a trailblazing surrealist is still filled with haunting dolls and grim paintings.

This modern arts center is built around a gem of late-Baroque architecture.

A Museum of Psychiatry in a still-operating mental institution.

Christ's blood preserved in a Belgian town.

This abandoned Belgian fortress is purposefully being left to nature.

Medical history with an amazing, if frighting, collection of wax diseases on display.

The morbid items in this small and hidden museum are not for the weak stomached.

This beautifully verdant lagoon is tucked below a massive volcano in a crater atop a black pebble beach.

A small church ornamented with medieval erotic sculptures.

This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

One of the world's oldest universities houses an incredible collection of anatomical models, mummified body parts, and human bones.

Devastated landscape used for hundreds of years by the Romans as their primary mining site.

Bold black and white motifs of life and death add a dramatic flair to this 17th-century crypt.

"Alleys of Stone" form natural mazes in Spanish natural park.

An architect transformed this abandoned cement factory into his castle-like workshop.

Partially collapsed lava tube and cave system complete with concert hall, underground pond, and unique albino crabs.

Bacteria and algae give the salty water its bubblegum hue.

At the foot of a waterfall lies a peaceful swimming lagoon and evidence of over 60,000 years of human habitation.

A gravity-defying "devil's bridge" that has a surprising architectural feature for its stability.

An enchanting monastery in the Spanish countryside appears lifted from a fantasy tale.