Mysterious rocks that ring musically when struck.

Where America's first doomsday cult awaited the end of the world.

Hellam Township is reputed to feature seven remote gates, which when passed through in the right order, open an entrance to hell.

A toxic ghost town sitting atop a massive coal fire.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

An abandoned cemetery lies in ruins as the surrounding forest swallows it whole.

World's first "penitentiary," meant to be humane, drove men insane.

A rock maze opens up to a panoramic viewpoint at an abandoned mine full of ghost stories.

"Dark Sky Park" is heaven on Earth for astronomers, one of the rare U.S. locations with no artificial light pollution.

This lush forest valley was once mined for lumber to the extent that it was once nicknamed "The Pennsylvania Desert."

Once the "Eighth Wonder of the World," this iron railroad bridge was decimated by a tornado.

Contrary to what one might expect, ice forms inside this small cavern during the summer and melts during the winter.

The little-known final resting place of one of America's greatest writers.

A journey through military artifacts and the history of Cortland.

2300-year-old Roman road connecting the empire.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

The underground sanctuary of a mysterious ancient cult.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

An alchemist's "magic door" stands in the middle of a Roman park.

Architectureal fantasy quarter of Rome.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

In upstate New York, gorgeous waterfalls and a watermill are slowly being reclaimed by nature.