A secret climbing tree hides along the side of a Costa Rican road.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

Ride a boat through this magnificent underground world, which now doubles as a theater.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

Constantly maintained, this organ is playing a six-century long composition by John Cage.

The world's first time capsule lies behind a welded steel door in Atlanta.

A local prank turned town icon.

The mysterious white squirrels of this Illinois city are treated like sacred cows.

Communism's topsy-turvy effect on Poland has been brought to life in this wacky tourist trap.

4,000 monkeys used for medical testing on an island off of South Carolina.

In paradise, feral pigs have claimed an island all to themselves.

These old stone ruins in the Oregon wilderness were once bathrooms and are steeped in legends of murder.

An eerie, derelict amusement park in Berlin.

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

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

The sound of swaying stalks in this stunning grove has been named a governmentally recognized sound.

The history of occult science is turned into a creepshow at this lurid Prague tourist attraction.

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

A winding path built in secret on the edge of the continent.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

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

This churchyard arbor is surrounded by hundreds of gravestones placed there by author Thomas Hardy.