The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

The 700-year-old fortress was the site of Count Orlok's castle in "Nosferatu."

The largest catacomb system in the world.

The birthplace of an eccentric alchemist and possible inspiration for the fictional reanimator of monsters.

Tubing through a cave lit with glowworms is a magical underground experience.

The bust of Romania’s most notorious ruler, Vlad Dracula aka "Vlad the Impaler," keeps watch over the ruins of his medieval court.

A hidden tunnel leads to an abandoned slate quarry that's now a secret swimming spot guarded by cliffs.

These layered sandstone mountains in China look like they are made of pressed crayons.

This vertical pinnacle in China was the inspiration for the floating mountains in the movie “Avatar.”

A sinkhole and now a swimming hole, too, full of dazzling turquoise water.

Raging waters have created a strange geological site that looks like something off of a progressive rock album cover.

Climb down into the largest sinkhole in Qatar.

After millennia of erosion by sand and churning water this Brazilian valley now looks like a lunar fantasy.

A massive natural rock arch gives the Tuscan mountain its own window to the sky.

A long, winding trek rewards you with a gorge so captivating it inspired a painting in the Tate.

Rare recess caves fill this unbelievably beautiful Ohio park.

Strange rock formations tower above the river that snakes through this enchanting Icelandic canyon.

An ancient Scottish rock formation said to be the gravesite of a giant remains ensconced in legend and intrigue.

Islanders once used this dramatic, otherworldly landscape to hide their cattle from Viking raiders.

The land is full of geologic eye candy, such as otherworldly spires, mushroom-shaped hoodoos, and prehistoric fossils.

During prohibition, corrupt city officials ran drinking dens under the streets of Downtown Los Angeles.

Portland had a unique approach to Cold War-era protections.

A mysterious castle built as a monument to lost love.

A little-visited waterfall in an otherworldly landscape.