Northern Ireland's Brobdingnagian stepping stones.

Amidst the bustling streets of Dublin, there is a hushed garden that is dedicated to "All those who gave their lives in the cause of Irish Freedom."

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

An ancient Egyptian temple in the middle of Madrid, Spain.

Opulence and fantasy collide in this royal chair which is supposedly made with unicorn horns.

The dome-shaped reservoir of this old water tower produces unique acoustic effects.

The original home of the Lego has a huge amusement park dedicated to the iconic plastic toy.

Eighty million natural history specimens call this gargantuan museum home.

Scattered throughout London are ancient remnants of the city's former bounding wall.

This one has sailed five times as far as Sir Francis Drake's famous ship.

This museum preserves the hand-dug tunnel that kept Sarajevo afloat during the Serbian siege.

Oriental bazaar in the heart of Sarajevo.

The place where World War I began.

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

Old Danish castle immortalized in Shakespeare's Hamlet.

Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

The old observatory in Copenhagen has a spiral corridor used as a racetrack.

Copenhagen's celebrated theme park and gardens.

Metro station with a claim to rock n' roll fame.

Cold war icon and onetime "hole" in the iron curtain.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

A Nesting Doll of Churches.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

Rome’s legendary peephole vista is also a former Crusader stronghold.