An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.

The place where houses are born.

Made of 41,900 pieces of mosaic, it took two years to piece together this giant egg.

A monument hidden in the woods built in 1938 as a getaway for a Dutch museum curator.

This dramatic landscape hidden on the Isle of Skye looks as though you've stepped into the magical realm.

The tallest mountain in mainland Netherlands isn't actually very tall.

While most bridges allow roads to pass over water, this one allows water to pass over a road.

This giant radio telescope would be a rusting ruin if it hadn't become such a beloved relic.

This towering church is home to a world-famous organ and a treasure trove of medieval art.

The Rozenberg wind wall in South Holland makes for smooth sailing through the Calandbrug canal.

This large copper bolt represents the benchmark for measuring sea levels in most of Europe.

This unique bridge physically lifts a piece of the road into the air to let boats pass by.

The ruins of this Dutch castle sit atop a labyrinth of once-secret tunnels and passageways, dating back over 900 years.

A beautiful maze marks where three countries meet.

American soldiers discovered Europe's best one-liner at the end of World War II.

The largest ice cave in the world is thought to be the entrance to hell according to Austrian legend.

The only museum with its curator—and her pets—buried inside.

The ruins stand as a somber reminder of France’s worst civil catastrophe of the 20th century.

This disused boat elevator was saved from the scrap heap so that visitors could tour its rusting skeleton.

On this romantic tidal island reachable only at low tide the tomb of a famous French writer overlooks the sea.

A unique zoological park home to over 30 species of wild cats, both big and small.

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

This ancient theater was once the home of fierce gladiatorial battles.

The world's tallest bridge is also possibly the most elegant.