This Luxembourg cave is covered in cryptic looking marks left by mining activity.

This noble mash-up in eastern Luxembourg is part Medieval, part Renaissance, all castle.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

Once the local rulers had gone these enchanting ruins housed common folk in an almost real life fairy tale.

This tri-part waterfall is a little bit of fairytale beauty in the heart of Luxembourg's Little Switzerland.

Amsterdam's Red Light District leaves little to the imagination.

In the middle of a forest you can find the first landing place of an air balloon in the Netherlands.

This large open-air museum showcases the ordinary lives of the people of the Netherlands and pre-industrial crafts and practices.

A farm turned upside down.

Located inside Hoge Veluwe National Park, this museum began as the private collection of a prominent female art collector.

A set of beech hedges planted in the 19th century forms a tunnel that takes on a different appearance in every season.

A striking memorial to the Jews of Leiden who were murdered during World War II is scattered throughout the city.

Now a museum, this building was once a 14th-century monastery and the place where the founder of the Dutch nation lived and was assassinated.

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

This artificial ring island was built to hold cubic tons of polluted dirt.

An idyllic hotel that gave its name to a supposed shadow government.

The Netherlands' first car tunnel has an unusually rectangular shape.

The nerve center of a massive, state-of-the art radio telescope that sprawls across Western Europe.

This gigantic monument hidden in the woods was built to thank the Dutch for sheltering Belgian refugees during World War I.

One of the largest burial mounds in the Netherlands and Belgium.

This 11th-century castle sits so low you can't see it behind the surrounding buildings.

A lecture hall sink once used by Einstein and other noted physicists is now regarded as a strange science relic.

People have been placing babies on these lilies for photoshoots since the Victorian era.

One of the oldest masonic temples in the Netherlands, built in 1757.