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

The portrait of a man from Japan who sent weekly letters to a Dutch hotel he never visited.

The elegant manor house where Kaiser Wilhelm II lived in exile after World War I.

Mosaics created from 11 million cigar bands.

This former hydraulic laboratory is now a woodland dotted with old engineering models.

A line number in Amsterdam that will likely never be used again due to its tragic history.

The place where houses are born.

A giant floating rubber duck-bunny painted with a different design every year.

Devious political maneuvering and four ancient, working telescopes are central to the world's second-oldest observatory.

Pull up and have a drink at a museum filled with hundreds of years worth of shipwreck artifacts.

The last of Amsterdam's original sea level markers remaining in place.

The tallest waterfall in the Netherlands is a lovely, stepped feature that is only 50 feet tall.

A late-medieval Dutch castle with trick fountains in its whimsical water gardens.

A UFO-shaped event building originally intended to be a science museum showcasing the future.

A grassy pyramid named after a French battle.

A miniature city, once ruled by the Queen of the Netherlands.

Take a stroll through the hellish grotesques of Hieronymus Bosch in this elaborate Netherlands church.

This subterranean studio is filled with fascinating kinetic art.

Three connected pink triangles memorialize persecuted gays and lesbians throughout history.

This impressive collection of rare books on ancient mysticism inspired author Dan Brown.