German and American troops joined forces to defend this fortress during the strangest battle of World War II.

The world's most important buildings shrunk to a tiny size.

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

Terrifically morbid cemetary and site of famous Paracelsus' grave.

Swarovski's museum/theme park is a fake diamond fantasia overlooked by a giant.

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

Abandoned blockhouses from Nazi Germany's Atlantic Wall erode into the sea on a French beach.

Longest canal tunnel in the world, abandoned in the 1960s.

This building’s ghostly exterior reflects its former lives as a prison, school, and funeral home.

This 1,400-year-old abbey was once a powerhouse for music and intellectualism known across Normandy.

Site of one of World War I's most horrific scenes.

A massive, secret marina for the Nazis' most formidable weapon in the Atlantic.

A French library that makes sure its love of books is writ large... giant in fact.

These crumbling Nazi artillery bunkers are now fair game for massive graffiti projects.

This ancient theater was once the home of fierce gladiatorial battles.

A swath of France so devastated by war it is still forbidden to go there.

The sunken structure looks like the victim of a catastrophic flood.

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

The Argonaute submarine was the French navy's pride and joy in the 1950's.

The world's largest reflecting pool is just two centimeters deep.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

Lyon, France is home to two remarkably preserved Roman theaters, one dating back to 15 BCE.