Two geological phenomena in one precarious locale: a towering stone window, and a deep blue void.

This unique building in the main square stands out among the city's typically Baroque architecture.

Burial grounds for more than 1,000 bodies deep under the modern town of Rabat.

The floor of this spectacular Baroque sanctuary is covered in memento mori.

The medieval home is still engraved with the symbol of the profession, an eye flanked by two axes.

A historic custom house with ties to George Washington is now a shrine to local nautical history.

Palatial mansion estate used in films including "Flowers in the Attic" and "The Witches of Eastwick."

An eccentric inventor's castle home with its own indoor weather system.

A living antique aviation museum in the historic town of Red Hook, New York.

In the mid-19th century, an eight-sided house was the latest fad.

Curtiss is a forgotten figure in the early history of flight.

This former theme park in New York's Adirondack Mountains fell into ruin before being resurrected as a state-run campground

Golden plates containing what would become the Book of Mormon were believed to be buried on this New York hillside.

A near tragic event on this bridge helped inspire the classic film "It's a Wonderful Life."

This oversize piece of novelty cookware once cooked the largest pancake in the world.

An abandoned asylum where patients have been forgotten but their possessions remain.

A rare tour of a commercial jet assembly plant, held inside one of the largest buildings in the world.

An abandoned network of military bunkers and tunnels open for anyone willing to descend into the darkness.

The grand marquee of this abandoned Hawaiian theater remembers the building's elegant past.

The air force base preserves its scars from the Japanese attack on Pearl Harbor.

The only royal palace on U.S. soil has been a territorial capitol, a military headquarters, and a prison for a queen.

This museum of Hawaiian and Polynesian culture is the legacy of the last descendant of the Kamehameha Dynasty.

This ancient cave temple complex is the largest and best-preserved temple complex in Sri Lanka.

This elaborate temple was built around one of the Buddha's teeth.