For years, the remains of this ancient Roman fortress were hidden under an orchard.

Every winter, this former planetarium is transformed into a massive, brightly-lit Christmas ornament.

An icon of International Style architecture on the outskirts of Rotterdam.

This vast World War II defense line was the site of a fierce battle.

Nestled in the woods lies this land art project: a hybrid between park, maze and natural monument.

This Dutch windmill has its roots in an American invention.

Watch the local Netherlands birds from inside this giant eco-egg.

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

A radio telescope for listening to the stars, based in one of the cloudiest countries in the world.

The struggle of a small Dutch island against the sea.

Scale model of St. Peter's Cathedral (Rome) in the middle of a small Dutch town.

The 20-mile causeway that separates the Netherlands from the sea.

This enormous storm barrier is one of the largest moving structures on Earth, with each arm taller than the Washington Monument.

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

The largest 19th century panorama in the world still in-situ.

Repurposed space and ultra-modern construction collide to create this geometric wooden spectacle.

This still-celebrated home was a radical architectural experiment in 3D De Stijl.

This steel frame is a skeletal mirage of a lost 16th-century stone building.

The world's first floating farm is staffed by one human, three robots, and 35 cows.

Home to the world's oldest functioning orrery.

This disused VLF radio station is no longer in service but the surrounding town still bears its name.

This historical Netherlands fortress still bears the marks of its single siege.

This 1920s Amsterdam neighborhood was built as a giant experiment in concrete construction.

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