This massive subterranean fissure is known as the "underground Grand Canyon."

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

This scale model of our solar system hid in plain sight for years before a physics team sought out all the planets.

This giant middle finger statue sends an unambiguous message to Italy's bankers.

These spooky and unusual stone formations create an underworldly landscape.

The tallest outdoor elevator in Europe rockets passengers on a dizzyingly precarious ride to the top of a mountain.

This Stone Age solar temple aligns with the sun on each equinox and solstice.

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

Steadily reminding Czechia of its past.

A series of playful yellow penguins share a serious message about the environment.

A steampunk-styled three-floor factory churning out art, activism, and electronic beats.

What looks like a crashed Zeppelin is actually a bright, airy reading room perched atop a modern museum.

A mocking tribute to the past and modern leadership of Prague.

A Jenga-style cylindrical tower of books that appears to go on forever.

Countless grotesque faces stare out from this eerie Prague art wall.

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

Thirty creepy ghosts now inhabit this decaying 14th-century church.

This former quarry is now a picturesque gorge that hides a sunken lake.

This spooky statue sits outside a famous Prague theater.

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

Each time a baby is born in Ghent, these streetlights flash in silent celebration.

Inside this former medieval prison is a collection of objects designed to inflict unbelievable pain and suffering on the human body and mind.

A little sculpture with a large wardrobe.