The palace window through which Protestant nobles flung two Catholic regents, thus sparking the Thirty Years' War.

A series of playful yellow penguins share a serious message about the environment.

A collection of anatomical samples from one of the first anthropologists to suggest that humans reached North America by crossing the Bering Strait.

Walk through Czech history in Prague's largest graveyard.

A Baroque mansion with ties to legendary magicians and alchemists.

A church of bones, decorated with 40,000 human skeletons.

Enormous sandstone towers loom within a Czech forest.

Naturally formed rock city in Poland.

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

The monument honors the first (and for a long time, only) African-born philosopher to teach at a German university.

The 3,600-year-old archeological sensation is considered to be the oldest representation of the cosmos.

The most visited, and possibly most controversial, museum in Germany.

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

Reminders of the Battle of Berlin still scar the railway.

A museum in the building where Nazi Germany signed its surrender tells the story of World War II from the Soviet perspective.

An imperial church bombed to ruins during WWII now stands as a jagged memorial.

For patriotic Russians, this memorial honoring the Soviet soldiers who died liberating Berlin in 1945 is the most sacred location outside of Russia.

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

Not many houses move across borders, this one did it twice.

This residence straddles a border between Belgium and the Netherlands.

This Netherlands museum holds a gloriously mechanical collection of ornate musical automata.

'The Letters of Utrecht' lays out a ribbon of poetry one letter at a time, with no final verse in sight.

Lumps of significant stone from around the world surround a flaming monument for peace.

A strangely curved lamppost stands tall over this avenue in Rotterdam.