The largest riverfront opening cave in the Ozarks.

On the cliffs of São Jorge in the Azores stand the remains of a lighthouse that was struck by a series of earthquakes.

The gloomy ruins that inspired Bram Stoker to bring Dracula to life.

Thirty creepy ghosts now inhabit this decaying 14th-century church.

The "Versailles of the Jungle" built by a dictator is now a decaying shadow of its hubristic grandeur.

This dilapidated ship carcass covered in trees is a striking sight.

These old stone ruins in the Oregon wilderness were once bathrooms and are steeped in legends of murder.

A 16th-century horror show built in a lovely Italian garden.

South of Bologna, a limestone grotto with a protruding waterfall and a floor full of cave pearls.

An abandoned amusement park turned street art gallery with open walls for visitors to spray paint.

The world's largest prehistoric copper mine had 30,000 animal bones scattered throughout the maze of passageways.

No one knows exactly how deep the world’s deepest geothermal hot spring is.

A six-story, asymmetrical tower filled to the brim with scientific experiments.

In 1912, this idyllic Alaska landscape was blown apart in the largest volcanic eruption of the 20th century.

The ruins of a grand theater destroyed during the most powerful seismic catastrophe ever recorded.

The hellish conditions of this abandoned mine that snakes beneath the Pacific Ocean gave it its diabolic name.

A French valley with forests so lush it was nicknamed "the Small Amazonia of the Pyrenees."

This futuristic observatory at the top of the Pyrénées offers unrivaled views.

Abandoned Nazi train station turned underground astroparticle laboratory.

This small archipelago in northern Lake Superior was formed by a massive meteorite impact 450 million years ago.

Built by an accountant with a dream of running a grand resort, this estate has sat vacant for over half a century.

The island houses the ruins of a secret nuclear fusion lab that once employed high-profile Nazi scientists

A brightly colored natural bridge formed by mineral-rich hot springs high up in the Andes.

A toxic lake near a volcanic caldera that is home to flamingos and other life.