Where commuters walk through remnants of an ancient Greek necropolis.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

Picturesque intersection of witchcraft and ancient Christianity.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

The hallucinogenic center of the ancient world.

A historic observatory now an astronomy museum beautifully situated at the moat of the Middle Age city centre.

This still-celebrated home was a radical architectural experiment in 3D De Stijl.

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

The spectacular history of spectacles on display.

This unattributed sculpture in Amsterdam is hiding in plain sight.

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

The former home of a mad diplomat is said to still be marked in bloody, arcane scrawls.

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

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

The largest collection of handbags in the world, the oldest of which were used to carry Bibles, primarily by men.

Cat art as far as the eye can see.

A beautifully eclectic mix of architectural styles.

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

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

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

Colorful and chaotic stacked hotel in North Holland.

The place where Czar Peter I of Russia resided in 1697 during his Grand Embassy.

Elaborate tile work in this railway station tells the story of Portugal.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.