Bermuda triangle lighthouse, site of mysterious disappearances, left to crumble into the Atlantic.

Rusting, graffiti-covered tanks litter the beach of this island, once used by the U.S. military for target practice.

The walls of America's oldest masonry fort famously "swallowed" cannonballs.

An abandoned vacation home spent a decade taking on legends. It's now taking on water.

An ancient burial ground believed to have been used for ritual sacrifice.

The complex has been abandoned since the Croatian War of Independence, barring a stint as a set for 'Game of Thrones.'

This amazingly well-preserved villa just outside Pompeii boasts rare examples of ancient Roman paintings.

Of course Salvador Dalí lived in a castle...

This sculpture commemorates Edinburgh's sister city and their respective celebrity dogs.

The U.K.'s first underground railway line is now a lively thoroughfare for runners and cyclists.

Once the product of an inexplicable gold strike, this ghost town is now home to one man and his love of classic machines.

On the outskirts of a reborn ghost town, a decaying post office remembers the bad old days.

In Tucson a giant metal snake helps pedestrians cross a busy highway.

The eroded core of an ancient volcano is now accessible by a short hike.

Bootleggers ran booze beneath this building before (and after) Route 66 appeared beside it.

This remote desert watering hole has a connection to a curious chapter of American history.

This 11th-century castle sits so low you can't see it behind the surrounding buildings.

This Arab fortress was once the largest citadel in Western Europe.

This volcanic plug boasts the longest recorded history of any Scottish stronghold.

This castle has links to Portugal’s founding and struggles for independence.

This home on a quiet suburban street is completely covered with vibrant mosaics.

A rare tour of an aristocrat's private home reveals valuable 17th-century paintings from artists like Rembrandt.

A magical sanctuary of mythological statuary.

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