A restaurant and observation deck built in a unique broadcasting antenna.

One of the best-preserved pieces of DDR propaganda in Berlin.

After local authorities changed the design, the building's architect, Le Corbusier, wanted nothing to do with it.

In the summer of 1957, a massive architectural exhibition showed off the future of urban living in this German neighborhood.

A socialist building dedicated to teachers showcases one of the largest Soviet mosaics in the world.

You've probably seen these distinctive orange-tiled columns on the big screen.

One of downtown Berlin's last reminders of its Communist past.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

A narrow passage next to a cafe leads to a courtyard exploding with murals, tags, and paste-ups.

A curious memorial to the Berlin Wall, German division, the war, and those who died at the wall.

A monument to the man who almost killed Hitler.

Berlin's old airport.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

A museum dedicated to the history of the diamond trade in the Netherlands.

Europe's first floating restaurant is home to a hilarious legend.

This unattributed sculpture in Amsterdam is hiding in plain sight.

This museum housed in a former brothel explores the past and present of sex work in Amsterdam.

These enormous concrete blocks played a vital role in one of history's most important days.

Before 1993, this historic-looking village—King Charles III's pet project—didn’t exist at all.

The world's only managed flock of mute swans was established as a factory for monk meat but is now an adorable sanctuary.

Want to properly offend a king? Sculpt a giant hill figure in chalk of him riding out of town.