An intricate and amazing house built by architect Karl Junker.

Skeletons dressed in extravagant 18th century royal costumes cavort in the aisles of this German basilica.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

Ruins of a German Castle on top of a towering stone pillar.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

A medieval church with largest and oldest collection of Renaissance frescoes in France.

A unique underground structure dating back to the 1st century BC.

A centuries-old complex of hand-dug stone chambers has sheltered locals in times of trouble.

The Church of the Annunciation was carved into the face of a cliff, just like the rest of the town of Haute-Isle.

The spiral staircase hidden inside this giant Parisian column was likely built for Catherine de Medici's astrologer.

An unusual number plate signifies the building's saucy past.

If they push on just the right spot, even the weakest person can move this titanic boulder.

The post-apocalyptic remnants of a bucolic town ruined by a plane crash.

A medieval military street hidden beneath a charming French fishing village.

A chapel on a volcanic core, marking the end of a successful journey.

Lyon, France is home to two remarkably preserved Roman theaters, one dating back to 15 BCE.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

A mosaic-tiled house built by graveyard sweeper Raymond Isidore.

This stunning French estate was so lavish that it landed its original owner in jail for the rest of his life.

Museum in a swimming pool where the water still flows.

This French castle is said to have once held the Holy Grail but is now a gorgeous mountaintop ruin.

Hundreds of secret cabinets built into the walls of legendary poisoner's private work room.

A natural arch carved by a river gave its name to the so-called "Cave of Forgotten Dreams."

For hundreds of years, automatons moving to metallic music have been marking the passage of time.