The second-largest gold nugget in existence, displayed in a Las Vegas casino conveniently named the Golden Nugget.

Northern Ireland's Brobdingnagian stepping stones.

This short bridge is the only thing connecting a tiny Irish island to the mainland.

This World War II relic let Allied pilots know they were entering neutral airspace.

The only remaining arch of the oldest stone bridge in Rome stands in the middle of the Tiber.

This curious, round temple is the oldest still-standing marble building in Rome.

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.