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

Legions of Roman soldiers bathed in this ancient spa complex under a Budapest transit station.

The Roman Emperor's lost summer home and grotto full of enormous sculptures sit along the Italian seashore.

A line of abandoned, alien-like fortresses dot the mountains of North Italy.

Once a bustling fishing port, this semi-ghost town is now more than 90 miles away from the shore.

The abandoned mine where American troops discovered a treasure trove of art and artifacts hidden by the Nazis.

You would never guess that before World War II this lonely field was a bustling German city.

A dilapidated dock tells the story of Titanic's missed arrival.

A moving memorial to the fallen and missing from WWI trenches.

The site where one of the most famous poems of World War I was composed is preserved to honor the legacy of the work.

This Belgian theme park began as a refuge for bored church children and was closed down when a boy lost an arm.

The vast chamber inside this abandoned cooling tower looks like something out of a sci-fi dystopia.

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

This sprawling Belgian fort was once thought of as impenetrable but now it is simply an abandoned relic.

This disused VLF radio station is no longer in service but the surrounding town still bears its name.

Cold war icon and onetime "hole" in the iron curtain.

Named after a militant urban guerilla, this famous former squat is a graffiti-covered stronghold of leftist culture.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

Berlin's old airport.

When German-Iraqi relations broke down, this embassy was vacated post haste.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

The music is over at the Ballhaus Riviera Ballroom, but the ballroom remains in haunting disrepair.

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