On rare days, this abandoned castle's gatekeepers open its doors, revealing the eye-popping splendor hidden inside.

The oldest teak bridge in the world is made from the remains of a royal palace.

"Satisfying" is a good way to describe these beautifully aligned rows of Spanish mills.

This surreal art house looks like a geometric version of a small chapel.

The oldest restaurant in the world is this old-world Spanish eatery, still known for its suckling pig.

A Hawaiian stairway to heaven—that you can't climb.

This mysterious Sardinian festival sees a horde of blank-faced equestrians compete for tin stars.

What remains of the summer palace of King Kamehameha III.

Lebanon's highest point offers expansive views, martian terrains, and eerie ski lifts.

Striking ruins of a mansion that stood center stage in one of modern Brazil's most puzzling crimes.

Hidden well off the beaten path in Catalonia is this crumbling medieval castle that is slowly being covered in graffiti.

A contemporary art installation housed within a Gothic cathedral.

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

These blingy, baubled skeletons lie in glass boxes inside a baroque Bavarian church.

The world's greatest slide descends 18 stories from this looping mountaintop viewing platform.

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

Since ancient times these picturesque springs have been providing bathers with healing waters.

A town trapped in time - 1958 to be exact.

Standing proud atop a Turkish bluff, this Ottoman palace has retained its grandeur despite being abandoned for centuries.

This legendary city has been a tourist attraction for centuries.

This historic stone bridge has an entire neighborhood clinging to its sides.

Africa's Venice on stilts.

Learn about Iceland's hidden folk at this school dedicated to the study of elves.

An Aztec temple, the largest man-made pyramid in the world, sits buried in earth with a Spanish church set on top.