This ancient Irish tower could easily have stood in for Rapunzel's prison.

The somber sculptures commemorating Irish Famine on the river Liffey in Dublin.

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

An ancient neolithic tomb that only sees the sun twice a year.

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

One of the oldest scientific gardens in Britain, containing more than 13,302 plant species in its core collection.

Touching this 18th-century Scottish philosopher’s toe allegedly conjures good fortune.

The final resting place of soldiers' loyal canine companions.

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

This walkway is so narrow it needs its own light to stop pedestrian traffic jams.

A stunning 18th-century site where pilgrims ascend by a series of punishing stairs only to return via funicular.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

One man's remarkable private collection of art from around the world.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.