This narrow Ghent alleyway is an officially sanctioned street art tunnel.

For years, the remains of this ancient Roman fortress were hidden under an orchard.

A preserved building where the dead were once watched for signs of life.

Thousands of tourists and residents in Cologne affix "love padlocks" on the Hohenzollernbrücke Bridge to symbolize their affections.

A church filled with the bones of hundreds of virgins martyrs—or so they say.

The largest bell in the world has been swinging high above a Cologne cathedral for almost a century.

If the tunes of antique organs and musical marionettes don't intoxicate you, the draft beer certainly will.

Lombardy poplars planted to imitate the size and shape of the Cathedral of Notre-Dame de Reims.

The birthplace of the ferocious William the Conqueror, this castle is awash in medieval history.

This enormous "cloth of the conquest" depicts the Norman invasion of England in mind-blowing detail.

This symbol of the French Revolution still stands where it was first planted during the 18th-century.

These unique markers designate the route American forces took during the Liberation of France.

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.

A memorial to the nearly 10,000 American soldiers laid to rest on the beaches of Normandy during WWII.

At the base of this tower, a plaque marks the original center point of the Netherlands.

The largest airborne operation in history was launched to capture this bridge.

This large open-air museum showcases the ordinary lives of the people of the Netherlands and pre-industrial crafts and practices.

Go inside a revolutionary, cage-less zoo where 70 species of monkeys roam free alongside their human visitors.

The elegant manor house where Kaiser Wilhelm II lived in exile after World War I.

A grassy pyramid named after a French battle.

This gigantic monument hidden in the woods was built to thank the Dutch for sheltering Belgian refugees during World War I.

This large sand dune in the Netherlands is home to wind-whipped trees with "floating" roots.