Street artists transformed an abandoned air vent into the beloved Star Wars robot.

Where lovers tie birch branches into long-lived knots.

The secret medieval communication system will whisk your words above the noise of the crowd.

England's only square-dimension hill horse was built to celebrate Queen Victoria's coronation.

Legend has it a commoner volunteered to be buried alive in the foundation so that the great fortress could be built.

A distinctive former power plant turned university lecture hall looks like it could make you breakfast.

The Cold War-era "underground Pentagon" is a sprawling subterranean hideaway for the Defense Department.

A 300-foot-long Cold War submarine floats in a Chilean River as a maritime museum.

This vintage animatronics show is the Vegas version of a walk through the woods.

A 4,000-year-old burial site hides behind a roadside Burger King.

19th-century scientists would make the pilgrimage here to verify the precision of their measuring sticks.

Left by the Devil, an ancient quarry or just plain old erosion, this enigmatic rock pillar rises 28 feet from the hillside.

Large, airy hallways hide within an impenetrable fortress that beckons urban explorers.

The first dish to bounce radio signals off the Moon, it was the forerunner to the U.S. Space Program.

A rare example of World War I trenches from the British front.

A medieval military street hidden beneath a charming French fishing village.

Impressive mining ruins overlook a spectacular view of Ireland's Copper Coast.

When a massive landslide hit one of the world's tallest dams it created a tragic environmental disaster.

Thanks to a spelling mistake this bizarre beaver-tiger hybrid became the symbol of a Siberian town.

The Incas turned this ancient Wari aqueduct into an imposing defensive gate.

An unsanctioned shrine that sprung up outside the late singer's home is causing a stir in London's Highgate neighborhood.

It's hard to believe the dizzying patterns covering this abandoned mine are completely natural.

This hulking behemoth is actually five interconnected towers built in the 1960s.

The world's oldest operational public pier railway has shuttled seagoing commuters from ship to shore since 1909.