The way that light hits a stained glass window on a specific day is one of many "clues" to a mysterious treasure.

French commune at the heart of conspiracies.

Green labyrinth formed by a karstic maze hidden in a preserved oak forest.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

Thanks to an acoustic anomaly, this unassuming stone bench has heard one hundred years of secrets.

The mysterious remains of a martyred teenage saint are venerated inside a small country chapel.

The oldest Roman lighthouse still in use.

This Navarrese cave's history of witchcraft and pagan ritual is not just embraced, but recreated each year.

Hundreds of prehistoric stones, arranged in perfect lines in a French field.

One of the great treasures of Neolithic art lies within this carefully constructed pile of rocks.

A massive, secret marina for the Nazis' most formidable weapon in the Atlantic.

Fighting the British and making game shows for over 150 years.

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

This ghost town in Belgium will lose its street art when it ceases to exist.

Rare wooden escalators lead deep down into an otherwise staggeringly monotonous tiled tunnel.

To enter this cluttered-yet-cozy sanctum of Belgian brews, ring the bell and tell the gatekeepers you've come “to taste beer.”

The legendary giant's severed hand sits on Antwerp's popular shopping street.

Most prolific publishing house in the 1600s open to the public.

An unassuming secret door once led to a legendary watering hole.

This ornate Weser Renaissance house was also the home of an infamous witch hunter.

The real life town from the Pied Piper of Hamelin has a mechanical puppet show that retells the famous story many times a day.

It took more than 300 years to build this church, which is home to two sacred vessels believed to hold the blood of Christ.

Concentrated around the Dead Sea, these surprising canyons are filled with coursing water, fish, and even crabs.

An early 20th-century sanatorium, long abandoned and now being reclaimed by nature.