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

Obelisks and stone pineapples in the Irish countryside.

A moody and picturesque riverside ruin overgrown with vegetation.

The oldest inn in Kilkenny was established by the first convicted witch in Ireland.

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

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.

This quiet bird sanctuary on the Danish coast is home to something not usually found in a conservation area: hunters' cabins.

This Danish castle is supposedly haunted by a woman too independent to not be a witch.

The decaying remains of a 1960s mechanical wonderland that never officially closed.

Iron Age "bog person" preserved for over 2,300 years.

Old Danish castle immortalized in Shakespeare's Hamlet.

A natural wonder in south Denmark.

This secret collection of the strange and occult was rediscovered in a forgotten room of an old house.

Six beautiful wooden giants are hidden around Copenhagen.

A walkable map of the world, made from soil and stone by one man.

Pre-Nazi swastikas adorn the sculpted pachyderms flanking this brewhouse portal.

A 19th-century subterranean reservoir repurposed as a contemporary art cave.

This picturesque island graveyard is the final resting place of dozens of notorious pirates.

The centuries-old trees lining both sides of this dirt road may become Madagascar's first natural monument.

A newspaper editor turned this abandoned island into a tortoise nature preserve that's now the world's smallest national park.

Over two-thirds of the world's population of giant tortoises live among this coral formation.