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

Italian cave with exceptional acoustics and an unsavory history.

The largest underground church in Europe.

A former utopian healing center created by a huckster and built by derelicts.

The "3rd largest" city in California is an empty mirage of suburbia in the middle of nowhere.

Where there's quartz, there must be gold. Thus is the story of the mines of Julian, and the titillating times of the Gold Rush.

A fake town founded by Western movie stars is now becoming a hip desert community.

The liveliest ghost town in the state.

This dark, quiet forest on the outskirts of San Diego is dense with rumor and lore.

Remants of foundations, streets, and streetcar tracks inhabit the cliffs where a landslide occurred in 1929.

The abandoned zoo enclosures offer a perfect place to experience the other side of the bars.

A natural gas leak provides a flickering flame beneath a waterfall.

Thousands of exquisitely carved stone water storage wells, hundreds of stone steps fill this exquisite medieval stepwell.

This natural French spring has been turned into a magical grotto by Roman and medieval constructions.

An ethereal glowing blue ocean cave in Croatia.

The ruins of an Estonian prison are drowning in the quarry lake where the convicts were once forced to work.

Tropical paradise strewn with hundreds of World War II wrecks.

A flooded Mexican cave that hides a river beneath the water.

Cavernous opening completely encased in Karst limestone.

The world's largest aggregation of great white sharks is at a mysterious spot in the middle of the ocean.

One of the deepest indoor swimming pools in the world.

Thanks to the building of a life-giving reservoir, part of the Great Wall of China is now a dive site.

This historic-shipwreck-cum-diving-spot can still be seen poking its boiler out of the Lake Michigan waters that claimed it.

The titular "little arch" near this Italian resort is one of the most popular diving spots in the country.