The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

A beautiful ruin of a 14th-century Plantagenet castle built by a medieval mercenary.

This landmark is a central figure in the Nez Perce origin story.

This medieval tower is all that remains of the castle where Joan of Arc was held before being burned at the stake.

Unknown to many, this sparkling turquoise lake hides amid Oregon's snowcapped mountains.

This unusual rock looks like a giant, otherworldly mushroom sprouting atop a cave.

Rare recess caves fill this unbelievably beautiful Ohio park.

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

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

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

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

Romania's "Red Ravine" is a little-known natural wonder that bears a resemblance to the Grand Canyon.

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.

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

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

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

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

This isolated island is often capped by its own fluffy cloud.

The sole surviving relic of the San Francisco neighborhood cobbled together from old horsecars and streetcars.

Thousand-year-old Viking runes adorn an ancient Greek lion at the entrance to the Venetian Arsenal.

No one's quite sure why there's a metal megaphone bolted on two rocks in the middle of the Mojave Desert.

Outstanding, eerie frescoes and decorations fill this 19th-century monastery.

William Smith's iconic "map that changed the world" is hidden behind a curtain in the Geological Society building.