Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

A Jenga-style cylindrical tower of books that appears to go on forever.

A plaque marks the spot where the saint was shoved off the Charles Bridge and into the river.

This automated sculpture of two men peeing will spell out text messages with their micturition.

This walkway is so narrow it needs its own light to stop pedestrian traffic jams.

The oldest garden in Prague, once part of an medieval orchard.

A sculpture of the iconic East German car on four legs is a tribute to those who traveled to Prague seeking asylum.

This historic little railroad runs through some of the most beautiful scenery in Germany.

The bridge that cost Germany a World Heritage Site.

Legend has it fairies gathered at the site of this medieval castle.

This scale model of our solar system hid in plain sight for years before a physics team sought out all the planets.

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

This narrow fjord-like bay is the largest ria in the Mediterranean Sea.

The Renaissance-era courthouse is a relic from the fortified town's centuries of Venetian rule.

Croatia's "hairy stone" fortress is one of the most well preserved Istrian castles.

Once a state-of-the-art tuberculosis treatment spa, these ruins are now ruled by paintball players.

This former estate of a fascist leader is now a burnt out ruin leading to a system of secret tunnels.

An eclectic art form practiced by untrained masters is celebrated at this museum in the heart of Zagreb's old Upper Town.

Where the lovelorn find a home for their sentimental keepsakes.

A World War II evacuation tunnel turned into a history display of Croatian state and people.

This 135-year-old weather station studied the effects of the climate on human health.

This truly palatial work of Communist-era architecture now sits crumbling on a Croatian beach.

This military tunnel dates back to World War II and provides visitors with a little wartime adrenaline.

Now abandoned, the world's first torpedo factory is crumbling into the sea.