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

This historic Amsterdam bar used to accept sailor's monkeys as payment.

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

The world's first zoo for microbes collecting the horrible and wonderful things living on and around us.

A floating cat sanctuary on an Amsterdam canal.

Cat art as far as the eye can see.

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

Take a stroll through the hellish grotesques of Hieronymus Bosch in this elaborate Netherlands church.

Fantastic views and thousands of love locks.

From Nazi chemicals to the CIA, this architectural marvel has played a fascinating role in German history.

The entrance to this Frankfurt subway station looks like an old tram car crashed into the concrete sidewalk.

The sweet story of how American cargo planes became known as "Candy Bombers" during the Berlin Blockade.

This abandoned coliseum was intended to be a grand Nazi rallying ground before it was halted at the end of the war.

A castle from the Holy Roman Empire that hosts traveling youth... in its stables.

During World War II, the Nazis repurposed this beer cellar to store stolen artwork.

This historic toy museum brings a little whimsy to a city not usually remembered for such things.

In this brilliant blue spring in Germany, legend has it that a sad mermaid learned to finally laugh.

The world's tallest church tower reveals a spectacular view to anyone up to the task of climbing the daunting staircase.

Albert Einstein's head sticks out of a snail shell stacked on a rocket in this truly bizarre monument to the scientist.

Legendary site where an evil bishop was devoured by rodents.

Tiny castle in the middle of the Rhine made you pay to pass.

A memorial for a young woman and her ghost, which are claimed to have caused countless deathly shipwrecks.

The birthplace of Karl Marx is now a museum dedicated to the communist revolutionary's life and work.

A top-secret bunker now turned museum, is an eerie look at what life would have looked like in the event of nuclear war.