The broken skateboards that became a poignant memorial to a murdered skater.

Eighty million natural history specimens call this gargantuan museum home.

The first green space constructed on an elevated viaduct.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the 20th century.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

The spectacular history of spectacles on display.

A hidden church in a hidden courtyard tells the story of the Miracle of Amsterdam.

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

A beautifully eclectic mix of architectural styles.

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

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

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.

Established in 1638 to battle the Black Death, this botanical garden is a treasure trove of rare flora.

Cat art as far as the eye can see.

This unattributed sculpture in Amsterdam is hiding in plain sight.