A 1,215-foot tunnel transports pedestrians beneath the River Thames.

A subterranean ice warehouse that has lain hidden beneath central London for over a century is now open to the public.

Winding paths and ramshackle mausoleums in the oldest "park cemetery" in London.

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.

The mysterious, fantastical woodland inspiration for "The Lord of the Rings."

Fluffy and friendly alpacas nestled against the border of the beautiful Connemara region.

An ancient chamber filled with wonderful rock art and a Neolithic carving of a human face.

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

The remains of this deep, dark mine have left behind a haunting rocky warren of tunnels.

A stunning Victorian abbey and walled garden on a lakefront.

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

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

The world's toughest modern Christian pilgrimage leads directly to the gates of Hell.

A spectacular hidden beach in Ireland has the dark, disturbing nickname of "Murder Hole Beach."

An unusual manor of stunning beauty, born out of a crippling disease.

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

The oldest pub in Ireland may also be the oldest surviving bar in the entire world.

The ancient tomb acts as a calendar that keeps perfect time.

This floating garden in the sky is straight out of a fairy tale, but the real thing is nothing short of magical.

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.

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

A former watering trough turned local heritage site.