A true Valhalla for cactus and succulent lovers.

The ruins of this Dutch castle sit atop a labyrinth of once-secret tunnels and passageways, dating back over 900 years.

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

A former plague hospital turned medical museum.

Unsurprisingly, Holland is home to one of the most magnificent flower gardens in the world.

Oldest Museum of the Netherlands is a true cabinet of curiosities.

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

This subterranean studio is filled with fascinating kinetic art.

The Bloemen Route, or “Flower Route”, stretches 25 miles through prime Dutch tulip country as a result of “tulip mania,” the world’s first economic bubble.

A Portuguese Jewish cemetery filled with stunning grave monuments that date back to 1614.

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

This small town in the Netherlands has no roads but instead, miles of canals and over 100 bridges.

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

The world's first zoo for microbes collecting the horrible and wonderful things living on and around us.

A curious collection dedicated to human and animal anatomy and pathology.

Cat art as far as the eye can see.

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

Museum preserving torture methods from the past.

A floating cat sanctuary on an Amsterdam canal.

This intriguing Bronze Age artifact spent centuries hidden within a Welsh faerie hill.

London's marvelous wildfowl reserve along the Thames.

This museum inside a museum tells the story of London's timepieces.

A wonderfully eclectic Victorian aquarium lies in the basement of the Horniman Museum.

Drink your espresso at a Victorian-era urinal in this underground-restroom-turned-coffee-bar.