There's a labyrinth of medieval chambers hidden deep below a 15th-century pub.

Harry Potter once visited this massive limestone cliff, which was carved by an ancient glacial river.

A typographic tribute to the many comedic greats who make Great Britain laugh.

Stonehenge has nothing on Castlerigg’s views.

Plundered and left asunder by grave robbers, this ancient necropolis has been painstakingly pieced back together.

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

Wander among the abandoned ruins of this once-powerful medieval town.

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

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

A moody and picturesque riverside ruin overgrown with vegetation.

A rocky Irish outcropping with a history of wealth, conflict, and ruin.

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

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

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

One of Ireland's most infamous prisons for rebels including men, women and children.

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

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.

Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.

Volcanic rocks ground down into sand make this Spanish beach as black as night.

Mine shafts and hard pastries await visitors at this massive mountain of salt.

Partially collapsed lava tube and cave system complete with concert hall, underground pond, and unique albino crabs.

A completely underwater art museum sends a stark message about humans' impact on the environment.

Bacteria and algae give the salty water its bubblegum hue.