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.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

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

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

Perfectly preserved ancient monastery in an impossibly dramatic location on a rocky island in the Atlantic.

Petrified footprints of one of the very first vertebrates to walk on land.

This single room has survived the centuries with almost no deterioration.

A stunning Victorian abbey and walled garden on a lakefront.

Traveling this mountain pass reveals quaint stone buildings, stunning Irish scenery, and a bridge said to grant wishes.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

The modern birthplace of Irish freedom.

An ancient neolithic tomb that only sees the sun twice a year.

A Neolithic passage tomb said to have sheltered two legendary Irish lovers.

The ruins of a medieval monastery named after a type of tree.

One of Ireland's most infamous prisons for rebels including men, women and children.

The final resting place of the poets Shelley and Keats.

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

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

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

The vast, legendary catacombs hold secrets much stranger than stacked bones.