A Nesting Doll of Churches.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

Architectural monsters are devouring this palace's every door and window.

Rome’s legendary peephole vista is also a former Crusader stronghold.

This collection of 20th-century toys is filled with a lifelong personal toy collection brought from the U.S. to Amsterdam.

Amsterdam's Red Light District leaves little to the imagination.

Tucked in the back of a flower shop, its collection details the fascinating history of the Netherlands's iconic symbol.

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

The history and future of cannabis.

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

The world's first underground farm is in a World War II bomb shelter beneath the streets of London.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the first ‘Harry Potter’ film.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

A former factory serves as a shrine to the industry that sustained Santorini for decades.

A quirky bookstore hidden beneath a sea of whitewashed Greek villas.

A Bronze age settlement on the Greek island of Santorini might have been the inspiration for Plato's Atlantis.

The first modern cemetery of Lyon is complete with more than 200 chapels and monuments.

A tiled, multi-level garden of survival in Lyon.

Hundreds of hidden passageways weave through the old quarters of Lyon.

A colorful piece of contemporary art cheerfully clashes with Lyon's historical architecture.

Lyon, France is home to two remarkably preserved Roman theaters, one dating back to 15 BCE.

A mysterious ancient elephant said to possess magic powers is now the symbol of a Sicilian city.

"Stairs of the Turks", a chalky white cliff eroded conveniently into stairs, allowing for easy pillaging.