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

The Vatican's secret porn-festooned bathroom was painted in erotic murals by one of the greatest artists of the Renaissance.

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

More sculpture than building, this architecturally significant temple was built on the spot of Saint Peter's crucifixion.

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

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

Behind the pink curtain, Au Bonheur du Jour, an art gallery of erotic archives.

The oldest stone house in Paris was built by its most famous alchemist.

One of the oldest medical collections in Europe focusing on rare surgical instruments.

Weird wax anatomical models reside here, as do other anatomical specimens.

Statue of death tucked in the University of Medicine courtyard.

A mechanized clock where a man fights off a dragon, crab, and rooster.

A museum on the history of Paris, including a set of Napoleon's toiletries, Proust's room, and relics of the Revolution.

A museum devoted to bringing to light forgotten or neglected histories through exhibitions, education and public programming.

The former home of a trailblazing surrealist is still filled with haunting dolls and grim paintings.

This former Masonic lodge has been transformed into part museum, part bar, all awesome.

A Museum of Psychiatry in a still-operating mental institution.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

Lavish royal estate punctuated with heated greenhouses.

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

A hospital where antique dolls are given new life.

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.

The plague quarantine island home to the alleged "Vampire of Venice."

This community on a small Venetian island has taken to painting their houses in bright neon hues.