This Art Nouveau mansion was used as the "House of the Screaming Child" in Dario Argento’s giallo classic.

Rome's first modern graffito is all that is left of a peaceful protest from the 1970s.

A modern sliver of architecture in Roma.

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

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

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

Hidden beneath a beautiful overlook you’ll find the history of the city depicted in comic strip format next to a pay toilet.

A once-secret library of Freemason history in Catalonia.

Many famous English poets including Elizabeth Barrett Browning are laid to rest at this Swiss-owned cemetery in Florence.

A slightly creepy gallery of plaster cast models in the same museum as Michelangelo's David.

An extraordinary house museum and cabinet of curiosities in the heart of Florence.

This strange bovine gargoyle is said to have been put in as a passive aggressive form of revenge.

A medieval weapon rumored to have been used by the brilliant poet himself.

The graveyard is filled with beautiful funerary art and boasts breathtaking views of Florence.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

This semi-secret storybook hedge maze is also the oldest garden in the city.

A beautiful but toxic fountain of mercury.

This cemetery features modernist statues as strange as its name.

An unusual stroll through gentlemen's erotica demonstrates that pornography is timeless.

Bask in the 19th century grandeur of an eccentric Freemason millionaire's private gardens.

A stately palace has been converted into the world's largest cannabis museum.

This cafe offers a curated collection of treats and tipples made by monks and nuns.

A cemetery in Barcelona's Poblenou district is home to this touching funerary statue, which depicts death in the form of a winged skeleton.

One of Europe's largest supercomputers is housed inside of a disused chapel.