The 14th-century ruins are said to contain healing powers.

A cheeky architectural easter egg.

Folklore says this medieval fortress was plopped atop a portal to hell to trap the demons below.

This unusually shaped mountaintop tower looks like a UFO floating over the city.

Bohemian paradise covered in majestic forests.

Mysterious standing stone formations looks like a petrified forest.

This tiny Bulgarian town offers a stunning location in the mountains and a storied history.

An 11th-century medieval castle cascades over the town of Numão.

A fortress off the West coast of Portugal that dates back to 1502.

This castle has links to Portugal’s founding and struggles for independence.

The medieval town's star-shaped walls are geometrically dazzling, though not entirely impenetrable.

In Portugal, a secluded stretch of untouched natural beauty hides at the bottom of a steep hill.

One of the largest Roman settlements in Portugal.

Local lore says the devil built this beautiful medieval bridge to help a fleeing bandit.

An early work of the architect Álvaro Siza Vieira, these swimming pools blend into the beach.

This gaping hole in the middle of a remote mountain lake looks like a portal to another dimension.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

Ivy-covered Medieval tunnels cut through this charming town in France's Loire Valley.

A striking symbol of the Bulgarian capital.

UNESCO-protected ancient burial ground.

In a long-dry lake bed, these groups of massive stone pillars bear a striking resemblance to clumps of everyone's favorite fungi.

A flamboyant five-story building in Bulgaria resembles a crawling snail.

This historic black and white monastery is one of Bulgaria's architectural jewels.

The ceiling of Prohodna Cave in northern Bulgaria affords a peek at the sky via two deity-sized-eye-shaped holes.