A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

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

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

A miniature train-ride through Slovenia's largest cave system.

The "dragon babies" of southeastern Europe.

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

A whimsical bridge adorned with decorative dragons.

A trough of 700 strange bronze faces runs through a narrow alley in Ljubljana's old town.

A relic from the Industrial Revolution got a second life as a contemporary performing arts space.

One of the largest caves in the world open to the public.

A floating cat sanctuary on an Amsterdam canal.

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

Amsterdam's former hotspot for public executions and dissections.

In the days before house numbers, these colorful signs held clues about various buildings' purposes.

Seven mini rowhouses fill the gap between 54 and 70 Westerstraat.

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

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

Established in 1638 to battle the Black Death, Hortus Botanicus Amsterdam is a treasure trove of rare flora.

One of Amsterdam's narrowest houses is located right across the canal from its widest.

A public urinal so pretty, it was declared a national monument.

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

Legend says this little-known stone circle is formed from people petrified as punishment for dancing on the Sabbath.

The alleged birthplace of Lady Jane Grey, who was executed at age 16 for claiming the throne of England.

This modern museum of Mediterranean culture is surrounded by a surreal concrete honeycomb.