A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

The romantic garden was the epicenter of the Hungarian art scene in the 1880s.

A Trabant car, a kangaroo statue, and a plethora of plants take over this abandoned-factory-turned-bar.

A series of caves under Castle Hill that once held the prisoner Vlad Tepes, better known as Count Dracula.

The hidden lair of an alchemist rediscovered in a 2002 flood.

A 400-year-old mummified arm dangles from the ceiling of St. James the Greater, serving as a warning to thieves.

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

A Baroque mansion with ties to legendary magicians and alchemists.

This artificial cave looks like something out of a fairytale.

Walk through Czech history in Prague's largest graveyard.

The history and future of cannabis.

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

A floating cat sanctuary on an Amsterdam canal.

Famed for its pie, this eatery has a hidden tunnel that allowed Catholics to secretly walk to church during the Reformation.

The world's only museum devoted to the wonders of fluorescence.

Cat art as far as the eye can see.

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

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

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

This massive mural by famed pop-artist Keith Haring was hidden for almost 30 years until its 2018 rediscovery.

100-windowed castle turned art gallery, built by one dedicated mason.

This salt marsh in Southern France is as pink as the flamingos that inhabit it.

Sleep in a climate-controlled plastic bubble for the night.

Artist Danielle Jacqui decorates nearly every inch of her home inside and out with her work.