This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

The abandoned Japanese amusement park once loomed as a dystopian Disneyland.

A submerged archeological park still holds the wonders of a Roman Sodom.

A seemingly endless landscape of pure salt stretches far across Bolivia.

A hand-built folk art installation covered with messages of God's love.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

One man has carved a number of natural New Mexico caves into psychedelic sandstone temples.

Notorious artist squat renovated into legal studios.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

The ghostly remains of an accidental sea.

An Australian lake whose pink hue defies scientific explanation.

The old Niles Canyon Aqueduct in the San Francisco Bay Area is a bemusing and secret trail through nature for wayward travelers.

Mother Nature outdoes herself with this stunningly beautiful set of caves carved into marble.

A one-of-a-kind collection of a unique medium.

Dramatic river bend surrounds a natural red-rocked pedestal.

World's largest collection of serial killer artwork and other macabre exhibits.

Most-visited and most-photographed slot canyon in the American Southwest.

On the Oregon coast there is a natural hole that seems to be draining the sea.

A lovers' beach, tucked below the surface of the island, provides a safe haven for romance.

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

Rippling sand dunes frozen in the Arizona rock.

A magical place that lets you play in and explore the world of Studio Ghibli.

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

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