Ancient rock-cut tomb? Definitely. That of a great Median king? Unlikely.

This 19th-century island fort built to protect against an invasion by sea.

A registered historic landmark shrouded in unsettling local legends.

A bridge that dates back to the 12th century is said to have made the devil very angry.

An architectural marvel that spans the Arda River, and has stories of a haunted past.

This unassuming alcove in London’s famous Tower Bridge once served to capture, store, and display dead bodies from the River Thames.

A mysterious bridge over a sunken Roman road.

This dreamlike museum is filled with the works of an influential surrealist artist whose name you may have never heard.

The 44,000-ton aircraft carrier was purposely sunk to create an artificial reef teeming with life.

Though nicknamed the “Russian Freighter,” this ship was actually sunk off the coast of Pensacola by the U.S. government in a top-secret operation.

A humid oasis combines recreation with exploration in a unique underwater cavern.

The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.

An underwater statue of Christ blesses the depths off Key Largo.

Spend the night in this formerly abandoned traditional Scottish village.

A network of concealed passageways lies within a busy London Underground station.

This collection of illusory paraphernalia has been culled from the history of London's premier magician's club.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

This macabre masterpiece of a mural is one of Francisco Goya's "Black Paintings."

The secret city built by the Manhattan Project.

A facility built in 1992 for an underground nuclear test remains in place today.

A phenomenal assembly of pueblos in New Mexico is the most complete example of ancient ruins north of the border.

A Neolithic celestial calendar standing in a nondescript wheat field.

Called the "Armenian Stonehenge," this ring of menhirs pierced with holes may be a prehistoric astronomical observatory.

Twisted trees shaped by coastal winds make this woodland look like something from a spooky story.