Amsterdam's former hotspot for public executions and dissections.

One of Amsterdam's narrowest houses is located right across the canal from its widest.

The former headquarters of history's oldest megacorporation.

An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.

The history and future of cannabis.

A public urinal so pretty, it was declared a national monument.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

An ancient ossuary in Rouen.

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.

Ghosts of France's colonial past.

1920's reinforced concrete church by architect Auguste Perret changes the face of modern design.

Inside this Jewish cemetery is a memorial to soldiers who deserted the German army and were executed.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

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

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

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

Tiny memorials honor individual victims of the Holocaust.

What started as a tongue-in-cheek shrine is now a full-blown museum celebrating "The Hoff" and his longtime love affair with Berlin.

This water-tower-turned-high-end-apartment building was once the site of an early Nazi concentration camp.

A prime example of socialist modernist architecture, wrapped in a enormous fresco about the media.

At one of Berlin’s oldest churches, visitors can place mosaic tiles to help restore a medieval mural.

Historic medieval fortified city in southwest France.

Art Deco stylings conceal the true nature of this bridge.

The California capital city once stood 10 feet lower than it does today.