A Nesting Doll of Churches.

The Pope’s secret escape route.

A forgotten "city of water" underneath the famous Trevi district.

In Rome’s Jewish ghetto, a 200-year-old bakery still makes the neighborhood’s historic sweets.

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

A fairy tale castle in modern Rome.

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

2300-year-old Roman road connecting the empire.

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

An alchemist's "magic door" stands in the middle of a Roman park.

Architectureal fantasy quarter of Rome.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

This Manchester laundromat is hiding something.

A glorious pub known for a spiteful printing feud and its famous typeface lost—then found—at the bottom of the Thames.

This luxury shopping lane has been protected by its own tiny police force for over a century.

London's largest outsider art museum.

This landmark church concealed a crypt packed with bones that was discovered thanks to the London Blitz.

A metal tree emits eerie, melodic notes on top of Lancashire's Crown Point.

The Columbia Road Flower Market is now open every Sunday, rain or shine.

Museum about life, death, and cannibalism in the Stone Age.

The names Lúthien and Beren can be found inscribed on the shared grave of the famous writer and his beloved wife and muse.

A historic arboretum and non-conformist, non-denominational park cemetery.

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