This abandoned but well-preserved Prussian fortress sits abandoned in a Polish forest near the German border.

This public park collects signposts and other memorabilia related to local history, Polish-German relations and human progress

One of only two places in the world where two rivers cross each other without the waters mixing.

A mysterious structure left behind on the Polish mountainside, sometimes called "Hitler's Stonehenge".

This fairytale medieval church in Poland originally spent centuries in Norway.

The tallest stone dam in Poland was opened by Kaiser Wilhelm II himself.

One of Belgium's oldest hospitals saw patients from the 13th to 20th centuries before becoming a museum.

This "social palace" housing complex created a relatively stable and self-contained worker's society... for a time.

Perhaps the most beautiful of preserved saints, with a little help from Paris.

A cave dwelling that was started by the Celts, expanded by monks, and finished by knights.

Live-in sculpture begun by one family in 1979.

The world's tallest bridge is also possibly the most elegant.

A well-preserved medieval village nested on a rocky outcrop and surrounded by a network of cliffs, natural bridges and canyons.

Historic medieval fortified city in southwest France.

An abandoned nightclub has become a vibrant work of art.

The history of knife-making in this French city is explored through this museum.

French Time Capsule-19th Century home revealed to the public.

The evocative ruins of a medieval village.

This mushroom-shaped rock has frustrated and fascinated locals for centuries.

This incredible stone temple is a monument to death, victory, and fantasy architecture.

This imposing castle has stood for nearly a thousand years.

Exquisite examples prehistoric bas-relief carvings.

Get a close-up look at a 16th-century Basque whaling ship at this factory and museum.

Climb atop one of the world's longest and heaviest trains for an unbelievable journey across the Sahara Desert.