The astonishing collection of an infamous criminologist.

This abandoned Brutalist treehouse is a hidden architectural relic.

This Roman arch marks the location of an ancient gate at one of the Seven Hills of Rome.

This shining multicolored metro station deep under Naples is said to be the most beautiful in Europe.

This real life asylum of horrors is now an abandoned ruin that hides the unbreakable code to one patient's insanity.

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

Giant, pink stuffed rabbit on an Italian mountain.

This former Roman Catholic Church still contains the embalmed hearts and organs of 22 popes.

This sword isn't waiting for a king to pull it out. It was placed there by a saint.

This giant middle finger statue sends an unambiguous message to Italy's bankers.

The middle finger of modernity.

A submerged archeological park still holds the wonders of a Roman Sodom.

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

The history of occult science is turned into a creepshow at this lurid Prague tourist attraction.

A 17th-century doorway in a small Sabine village is a portal into the mysteries of alchemy.

A medieval house with mysterious alchemical inscriptions on its facade

Legend says this mysterious stone head belongs to a woman who was petrified by an alchemist.

A museum of alchemy and a basement laboratory all housed in an ancient building in a Gothic tower.

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

The hidden lair of an alchemist rediscovered in a 2002 flood.

The birthplace of an eccentric alchemist and possible inspiration for the fictional reanimator of monsters.

In the middle of downtown Brooklyn lies a 165 year old secret hidden right below the surface (closed to the public indefinitely).

A reclusive Memphis neighborhood is home to decades worth of misunderstood Masonic folk art.

One of the oldest masonic temples in the Netherlands, built in 1757.