The fairy tale castle of the "fairy-tale king."

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

The severed head of a 17th-century Irish martyr lies within an intricate golden shrine.

This Bronze Age tomb is the centerpiece of a clearing within a beautiful Irish forest.

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

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

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

Oliver Cromwell once seized the land under this house, which included the ruins of a medieval abbey that the owner used to build his stately home.

A stunning Victorian abbey and walled garden on a lakefront.

After being destroyed by IRA sympathizers, the ruins of this stately Irish manor have sat vacant for decades.

Experience what life was like in Ireland during the Viking and medieval ages.

More than 5,000 artifacts donated by the people of the city, plus a room entirely devoted to the band U2.

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

While only two of the ancient buildings at this site are actually churches this was one of the earliest Irish pilgrimage sites ever.

The mummified heart of a saint lives on in this church—after a brief hiatus when it was stolen.

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

Obelisks and stone pineapples in the Irish countryside.

The enchanting archway is the only surviving portal into Dublin's lost medieval wall.

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

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

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

A tiny microvalley etched into the side of Knocknarea Mountain hides another world.

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

A floating museum that was sunk by a flood and left to rot in the tides.