Built to transport German U-boats through the never-completed Masurian Canal, the locks near this Polish village are now home to a rope course.

This railroad track was so secretive that it was omitted from all maps.

A massive work of modern art that appears to be a crop circle in the middle of the desert.

An alien landscape of chalk-rock in the Egyptian desert.

The struggle of a small Dutch island against the sea.

Slum Settlement Filled With Mountains of Garbage.

A hyper-remote desert cave dramatized in "The English Patient."

This remote, abandoned Soviet observatory promises spectacular views for those who can reach it.

Edoras, capital city of Rohan in Lord of the Rings, once sat atop this isolated New Zealand mountain.

This overlooked street light once served as a KGB dead letter box.

You may recognize this beautiful grove within Kaitoke Regional Park as location of the house of Elrond.

This single-track road rewards brave drivers with stunning Scottish scenery.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

Rippling sand dunes frozen in the Arizona rock.

Denmark’s never-ending bridge.

Though these human-made islands were constructed as an escape for the wealthy, they rarely see many visitors.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

This Vietnamese hell cave lets visitors take a walk through a devilish underworld full of demons.

This 200-meter-high waterfall marks the site of Achilles’s immortal baptism at the mouth of the River Styx.

Poseidon? No one seems to know.

A geological oddity topped with a 2,000-year-old pagan temple.

Is this 47.7-mile stretch of highway the longest straight road in the United States?

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.