The underground sanctuary of a mysterious ancient cult.

The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.

The yawning maw of this pagan visage is said to bite off the hands of liars.

Contains some of the world's more disturbing wax anatomical models.

A dismembered holy head stares out from her beautiful reliquary at the St. Dominic Basilica.

Inside this building is another country within Rome, a sovereign entity without a physical territory.

This basilica is dedicated to two saints, one of which is known more for his famous quote.

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

This hydrochronometer was invented by a Dominican monk and is a prime feature in this garden.

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

The Pope’s secret escape route.

Breathtaking and huge 430 year old maps of Italy.

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

If you want to talk to the Pope you will have to stare down this surreal vision of Jesus rising from a nuclear hell.

France's most famous cemetery, with some of its most curious tombs.

The spiral staircase hidden inside this giant Parisian column was likely built for Catherine de Medici's astrologer.

This bridge was constructed from the rubble of the infamous Bastille.

The celebrated eyesore created by starry-eyed sweethearts.

This demon atop the Notre-Dame de Paris looks utterly bored.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

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

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

Site of a classic 19th-century physics experiment to prove the earth is rotating.