This Budapest bar allows drinkers to leave their mark on the walls, floor, and even ceiling.

A 19th century artistocrat's mansion, turned into a library, hidden in a modern library.

Op-art architecture designed for happiness.

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

The beautiful baroque library of the Hapsburg empire.

Baroque celebration of the end of the Great Plague of Vienna.

An Austrian house of bones filled with hundreds of intricately painted skulls.

Trick water gardens from 1619 featuring a 200 piece mechanical theater powered by water.

The tunnel's elegant proportions keep you snug with no claustrophobia freak-out.

This automated sculpture of two men peeing will spell out text messages with their micturition.

Macabre astrological automaton clock dating to the late 1400s.

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

Looming communist pillar with a Czech twist.

Increasingly decayed figures stand as a powerful reminder of the human costs of Czech Communism.

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

This short bridge is the only thing connecting a tiny Irish island to the mainland.

Northern Ireland's Brobdingnagian stepping stones.

The atmospheric road was never meant to be so creepy.

The ship built to ferry passengers and goods to the doomed Titanic is now the last remaining White Star Line vessel.

This singular Irish dolmen is more Frank Lloyd Wright than upright stonehenge.

A hugely vast Irish landscape of barren rock that stretches for miles.

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.

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