Remains of the artificial harbours invented for the Allied invasion of Normandy can still be seen at sea.

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.

You would never come across this tiny green oasis if you didn't know it existed.

Hiding the longest subterranean river known in the world.

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

Sculpture designed by Turkish artist and professor Mehmet Ali Uysal.

A Belgian self-built tower inspired by the Bible and ancient civilizations.

These ruins reveal the remarkably intact layout of a Roman marketplace.

Part modern art project, part traditional chapel, this see-through church is only substantial from the right angle.

An open-air sewer system that was covered piece-by-piece over 300 years.

The patron of this extravagant Art Nouveau confection insisted that nothing less than a boat should project from its facade.

A 14th-century fortified keep showcases the masterpieces of an ingenious 20th-century clockmaker.

This modern arts center is built around a gem of late-Baroque architecture.

A fantastical 13th-century fortification sandwiched by a modern hotel in central Brussels.

Cozy basement bar sports an inventory of over 2,000 beers.

This Greek temple, open only an hour a day, was the site of a war of tastes between an architect and an artist.

Ancient man-made caves underneath small town Belgium.

The tiny Belgian town's ancient version of Mardi Gras involves eerie wax masks, sticks for warding off evil, and ostrich plume hats.

A village of art and exotic creations.

A daring D-Day assault by U.S. Army Rangers is commemorated atop the high cliffs of this strategic point.

Resting on a hill overlooking the coast, these medieval ruins look completely deserted save for their restored chapel.

The industrial architecture honors the laborers who brought the Exposition Universelle of 1900 to life.

The ruins of a medieval castle linked to the murderous French lord that inspired the famous legend of Bluebeard.

100-windowed castle turned art gallery, built by one dedicated mason.