A 19th-century British industrialist built this Louis XIII–inspired chateau for his homesick French wife.

A 'living museum' in Leiden, the oldest of its kind in the Netherlands.

This impressive collection of rare books on ancient mysticism inspired author Dan Brown.

This basement museum explores the art and artistry of fascism.

A set of seven houses, each built in a style that represents a European country.

A collection of biblical memorabilia.

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

This unattributed sculpture in Amsterdam is hiding in plain sight.

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

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

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

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

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

Cat art as far as the eye can see.

A floating cat sanctuary on an Amsterdam canal.

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

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

The attic of a four-century-old canal house hides a clandestine church.

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

This informal museum is a magical trove of anonymous art collected from car boots and flea markets.

The mouldering remains of a disgraced British children's icon are hidden in the brush of a public park.

This secret garden has bloomed into London's most unique hub of urban creativity.

A comic book store that puts the marvel back in marvellous.

A monument dedicated to the unrecognized Black "mother" of modern medicine.