This collection of over 50 murals celebrates Brussels' rich history as the self-proclaimed home of the "comic strip."

Climb inside an iron crystal magnified 165 billion times its normal size.

Stockholm's narrowest alley is barely over two feet wide.

A statue of Paulina Hermann, the eccentric noblewoman known as the "mother of cats."

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

An underground city of salt.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

A whimsical bridge adorned with decorative dragons.

Martin Bricelj Baraga's monolithic sculpture measures the blueness of the sky, and changes color to match it.

This abandoned Slovenian military barracks has become a punky-political art squat.

This one-time health resort was used by aristocrats around the world.

Trimmed trees grow alongside the graves like topiary tombstones.

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.

Island wonderland for communist autocrats.

The big toe of this towering monument to a Croatian national hero is worn from years of superstitious rubbing.

This beautiful Croatian fortress is haunted by legends of forbidden love.

This abandoned Croatian stronghold never saw a great deal of conflict but it is still a beloved relic nonetheless.

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

Now harmless, this looming post struck fear into the heart of medieval troublemakers.

An ancient knight and a symbol of the city's freedom.

A tower marking the spot where Yugoslavia began its resistance against the invading Nazis stands neglected, but not quite forgotten.

Croatia's towering concrete blossom grows from the site of a World War II concentration camp.

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