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

This road in the Great Smoky Mountains was supposed to assuage a displaced community, but ended up a $52 million dead end.

A psychological self-portrait in the form of a giant, segmented head.

Bohol's mysterious brown hills.

A salty red wasteland in Tanzania is a breeding spot for endangered flamingos.

Despite its name, this route in southern Utah offers a heavenly day trip.

Before he was America’s most famous preservationist, John Muir was an ingenious mechanical inventor.

More than 100 monumental tombs carved into rock are preserved at this ancient Nabataean site in the Arabian Desert.

The world's highest and most dangerous infinity pool lies at the precipice of Victoria Falls.

Groups of prehistoric tombs that dot the mountains of northern Oman.

This bazaar is one of the oldest in the Arabian world.

The only natural lake in the world that drains into both the Atlantic and Pacific Oceans.

A series of modernist treehouse hotel rooms grace the outskirts of an Arctic forest.

Get lost in this haunting fairytale art walk through a man-made eucalyptus grove.

Longest canal tunnel in the world, abandoned in the 1960s.

This Costa Rican topiary park is a surreal garden of unearthly delights.

This small group of sand dunes manages to pack in a strange rainbow of colors.

This former Cyprus flight hub is now a crumbling, abandoned ghost complex.

This cluster of little wooden huts once ground local farmers’ wheat into flour during the days of the Austro-Hungarian Empire.

Odd outsider art installations surround a Gold Rush-era ghost town.

Germany's Glienicke Bridge has a shady history of clandestine meetings, espionage, and spycraft.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

Raging waters have created a strange geological site that looks like something off of a progressive rock album cover.

For a brief time in 1960s France, families could climb into a tiny submarine and be pulled along an underwater journey.