People in Poland have rallied to save this unnatural desert from being reclaimed by the forest.

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

While the U.S. and Soviet Union were engaged in a space race, Poland built a UFO on the ground.

This massive blockhead sculpture hides an entire library.

A well-preserved medieval village nested on a rocky outcrop and surrounded by a network of cliffs, natural bridges and canyons.

Historic medieval fortified city in southwest France.

The haunting cadaver tomb of a famous French poet, playwright, and filmmaker.

Giant topiary dog once played a role in a terrorist bomb plot.

This 19th-century fountain's namesake animal isn't what you think it is.

An abandoned 6th-century monastery features a medieval map of the known world.

A small church ornamented with medieval erotic sculptures.

This house covered in small stones was the work of one man over the course of nearly 30 years.

The ruins of the second-largest circus school in the world.

In Spain, the ruins of a Roman military camp sit along a flooded section of a river.

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

One Portuguese poet described this cape, the westernmost point in mainland Europe, as "where the land ends and the sea begins."

The verdant mossy ruins of a Franciscan monastery lie in the remote Sintra hills awaiting exploration.

A unique seaside cave where Aleister Crowley faked his own death.

Perhaps the most spectacular grotto along the Algarve coastline.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

Tucked away inside this concrete building is a church and its grand display of brutalist architecture.

This once-forgotten oasis in the middle of Lisbon was first created over a century ago quite by accident.

This unassuming chapel in Portugal plays host to a ghoulish collection of bones.