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

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

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

The steepest classic funicular in the world glides along a dizzying incline.

The fairy tale castle of the "fairy-tale king."

Folklore and history carved into Brittany's coast.

Walk through living pictures and music in the Cathedral of Images.

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

This structure atop a craggy cliff in one of the most beautiful parks in Paris boasts an unbeatable view.

A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

This Paris art space celebrates the creativity and ingenuity that springs from abject poverty, especially in Africa.

This surreal statue brings a famous French novel about a supernatural cad to arresting life.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

In the best of all possible worlds, everyone will get a chance to see this statue in which Voltaire's heart is interred.

The ruins of a Duke's bucolic dream, where camels once roamed alongside "Dutch" windmills and faux-Italian vineyards.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

The very center of Paris is surrounded by a bevy of strange good luck rituals.

Paris' linguistic guide to the international language of, yes, love.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

Notorious artist squat renovated into legal studios.