Head underground and take a tour of the city's working sewer system, and see the underground river Senne, which defined Brussels for centuries before being covered in the 19th century.

A little sculpture with a large wardrobe.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

The Devil’s own choice when he needs a drink in Brussels.

Climb inside an iron crystal magnified 165 billion times its normal size.

An effigy of a trapped paratrooper dangles from a Normandy church to commemorate one remarkable D-Day event.

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

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

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.

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

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

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

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.

France's most famous cemetery, with some of its most curious tombs.

A small island dotted with old, historic Finnish buildings.

Crawling into this primordial cave may feel disconcertingly familiar.

This irregularly shaped sea fortress has defended not one but three different sovereign states.

While the U.S. and Soviet Union were engaged in a space race, Poland built a UFO on the ground.

In the midst of a living monument to Soviet social engineering, Polish Catholics built this church by hand.

This tower in a small Polish village uses the power of a sacred bell to ward off mischievous weather spirits.

This sprawling concrete suburb of Kraków was designed by the Soviet Union as the model proletarian city.

An underground city of salt.