The heroic sled dog of the 1925 serum run is preserved in taxidermy.

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

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

A standing relief of a Norman knight whose posture marks him as a Crusader.

Once the longest bridge in Ireland, this rusting span sits abandoned and overrun by nature.

This Irish show cave is said to have been the site of a Viking massacre that claimed 1,000 lives.

This ancient Irish religious site is covered in ancient carvings, many of which have barely aged.

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

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

An Iron Age fort on the edge of a seaside cliff offers a glimpse into an ancient, mystical world.

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

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

Ireland's most remarkable collection of these curious cone-shaped houses is worth the buzz.

Just a few miles off the western coast of Ireland lies an isle steeped in Irish literary history.

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

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

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

Though they've since been renamed, these two streets hint at Dublin's darker days.

This permanent collection of preserved bodies taken from Irish bogs is one of the leading authorities on such morbid mummies.

An Irish church where an 800-year-old mummy is reaching out of his coffin as if to shake hands.

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

Huge masonic hall in Philadelphia with lavishly themed rooms.

World's first "penitentiary," meant to be humane, drove men insane.