This famous Nevada gold mine, once a hotbed of Wild West shenanigans, is now open for tours.

A volcanic tunnel illuminated by natural skylights offers a shaded respite from the desert sun.

Its dark depths conceal millions of rare, delicate crystal formations.

It was once used as a classroom to teach mining skills to local high school students.

A winding, blood-red tunnel of hardened lava navigable by foot.

This abandoned Soviet circus is slowly being restored to its Communist-era glory.

The only residents of this abandoned housing development full of identical castles are stray cats and dogs.

One of the largest wooden constructions in Europe was meant to be a casino, but soon became an orphanage.

The social hall of this former factory is a Communist-era time capsule.

This enormous abandoned prison was once dubbed the "Bastille of Romania."

The romantic botanic tunnel feels like a well-kept secret.

Ruins of an old water tower that look like a horror-film castle.

A beautiful 19th-century mansion slowly crumbled and became a 'ghost house' after World War II.

An abandoned monument remembering the "Pančevo Holocaust" now stands as a shadow of its former self.

This abandoned Olympic skiing facility still bears the scars of the Siege of Sarajevo.

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

On rare days, this abandoned castle's gatekeepers open its doors, revealing the eye-popping splendor hidden inside.

The abandoned ruins of a failed resort hide on this verdant, picture-perfect island.

This amazingly preserved Doric temple was abandoned before it was ever completed.

This entire town moved to a safe location after it was devastated by an earthquake, but the remains of the original town are still around.

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

Four-story concrete hotel never opened to customers.

A hulking remnant of Alaska's industrial gold mining boom in the 1920s.

Plenty of old carney magic still haunts this photogenic amusement park.