The oldest stone house in Paris was built by its most famous alchemist.

Abandoned railway line circling the city of Paris.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

A monument to the man who almost killed Hitler.

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

The walls of Germany's Parliament still show the scars of the Red Army takeover in World War II.

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

The site of the famous Nazi book burning campaign of 1933 remembers its "Night of Shame".

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

A surreal museum of extraordinary industrial objects.

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

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

An eerie, derelict amusement park in Berlin.

This Funeral Hearse Museum represents the finest in cadaver transportation.

Turntable anonymously received orphans, alms, and groceries.

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

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

A unique collection of gilded age mechanical pianos.

Three connected pink triangles memorialize persecuted gays and lesbians throughout history.

This is what trains will look like after the zombie apocalypse.

The abandoned "Red Star Train Graveyard" is the final rusting place for precious artifacts of train history.

The Belgian royal family's private depot now stands abandoned and forgotten alongside the tracks.

This tiny traditional smokehouse is the only one left in this historic fishing port.