A remarkably intact castle that once was the largest in Ireland.

A gated cross stands on the site where an Irish revolutionary met his end.

A Bronze age settlement on the Greek island of Santorini might have been the inspiration for Plato's Atlantis.

The fountain marks the area where hundreds of accused witches were burned at the stake.

Enter this small nook and you'll be surrounded by 360 degrees of street art.

A pair of stones embedded in an Edinburgh street memorialize one of the city's last public hangings.

This memorial was created by an Irish nurse who lived in New York City during 9/11.

A former factory serves as a shrine to the industry that sustained Santorini for decades.

Local legend says the remains of Father Christmas lie within the medieval grounds.

The Scottish Reformation leader's grave was paved over and is now a parking lot.

Eclectic final resting place of the controversial explorer.

A teddy bear sits on a chair watching the sunset from the mountaintop—just as the late Dan Clancy had done since childhood.

An important landmark in the history of algebraic logic.

These imposing walls and towers look more like the ruins of a fortress than a monastery.

This 14th century tower house was once the home of Irish poet W.B. Yeats.

A strange egg in a mucky bog of western Ireland marks the spot of an aviation milestone.

Impressive mining ruins overlook a spectacular view of Ireland's Copper Coast.

An ancient holy well said to be used by the patron saint of sailors and travelers, lost in the boggy west of Valentia Island.

An abandoned faux-pub made famous by a Guinness commercial.

On the Irish coast, 18 members of the Howard family are eternally resting in an Egyptian pyramid.

The skeleton of a whale that beached itself in this Irish town is now on display in their public park.

An important pilgrimage site for pagans and early Christians, named for a Celtic goddess-turned-saint.

You can see three Irish counties from this Neolithic hillside fort, once the seat of the Kingdom of Ailech.

A collection of housewares from recent Irish history adjoined by a tower from ancient Irish history.