A massive underwater sinkhole made famous by Jacques Cousteau.

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

The ghostly remains of an accidental sea.

An enormous, inside-out glass globe built in 1935.

A trash dump made beautiful by nature's power.

A fiery crater has been burning in the Karakum Desert since 1971.

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

Dramatic river bend surrounds a natural red-rocked pedestal.

An ancient capital city that dates back 3,000 years old and harbors many surprises.

Tucked in the back of this amazing antique store is an important piece of medical history.

A beautiful, dense forest in the shadow of Mount Fuji, with a tragic reputation.

Medicinal spa created with the discharge from a geothermal energy plant.

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

The neon signs from Las Vegas' past find their final resting place at this unusual graveyard.

An artsy hidden staircase leads to breathtaking views of San Francisco.

Rippling sand dunes frozen in the Arizona rock.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

A terrific purveyor of natural history objects and curios.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

On Japan's Tashirojima Island, cats are king.

A huge musical instrument played by the ocean.

Skulls from the plague of 1656 and World War II bombings are united by a cult dedicated to caring for the ancient dead.

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

The yawning maw of this pagan visage is said to bite off the hands of liars.