The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.

An exquisite tunnel of cascading flowers.

An eerie, derelict amusement park in Berlin.

This geothermal hot spring hides beneath a slowly growing mineral dome.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

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

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

A swing to dangle you off the very edge.

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

Rippling sand dunes frozen in the Arizona rock.

A theme park that suffered massive flooding during Katrina was abandoned, and now proves irresistible to trespassing explorers.

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

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

A church of bones, decorated with 40,000 human skeletons.

An emerald-green grotto just a short trip from Austin.

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

On Japan's Tashirojima Island, cats are king.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

Hundreds of trees made from glass bottles make up this forest on Route 66.

In the middle of an extremely unforgiving and desolate high desert is the most secret military facility in the world.

Costumed elves and mountain bikers co-exist peacefully at this abandoned Christmas-themed adventure park.

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

One of the largest, oldest, darkest, quietest motel rooms in the world.

This abandoned horse racing track was an exercise in hubris from its inception.