This unattributed sculpture in Amsterdam is hiding in plain sight.

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

A floating cat sanctuary on an Amsterdam canal.

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

The attic of a four-century-old canal house hides a clandestine church.

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

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

A surreal museum of extraordinary industrial objects.

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

A monument to the man who almost killed Hitler.

A museum dedicated to a Cold War era sausage.

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

Floating swimming pool within a moored vessel.

Where once there was a train station bathroom, there is now this German burger joint.

A museum dedicated to the history of a terrifying secret police is now held in their former headquarters.

A 12th-century fortress containing some of Berlin's oldest buildings.

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

A scattered trail of street art adds a pop of color to the city's stark structures.

A sulfuric martian landscape that looks far better than it smells.

This stunning concert hall has become a symbol of Iceland's national recovery.

This beautiful, historic church looks like something out of a simpler past.

The rogue roots are gradually consuming some of the historic marble grave markers.

On the Fourth of July this area will transform into a Pompeii-like storm of falling embers and ash.

Soldiers were buried next to Lee's house in the center of Arlington Cemetery to dissuade the general from reclaiming his property after the war.