Hidden beneath the streets of London is a secret subway that only carried mail.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

William Blake claimed to have painted this gothic masterpiece after encountering this nightmarish being in a vision.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

Museum dedicated to literary greats of the Romantic Period is also the home in which Keats met his untimely end.

This historic recreationist school churns out warriors that may very well have had a fighting chance in Rome's pits of the day.

The underground sanctuary of a mysterious ancient cult.

In the early Roman Empire, people deemed traitors and criminals were tossed to their deaths from this rock.

This curious, round temple is the oldest still-standing marble building in Rome.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

This hill made entirely of ancient Roman jars was simply a garbage dump to the people of the time.

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

This large, circular tomb is the final resting place of the first emperor of Rome.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

Architectureal fantasy quarter of Rome.

A collection of objects supposedly singed by the hands of souls in purgatory.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

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

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

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.