These 500-year-old frescoes depict the city in its glory days.

This giant middle finger statue sends an unambiguous message to Italy's bankers.

Third time's a charm, or in this case, two testicles are.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

Museum dedicated to the terror regimes of Hungary.

The metal leaves on this tree are engraved with the names of Holocaust victims.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

From cartoon characters to tiny tanks, a guerilla sculptor's little bronze statues are hidden throughout the city of Budapest.

A triumphant marble and bronze fountain depicting a 15th-century Hungarian king and his hunting party.

The geographical center of Budapest is marked with a 10-foot-tall stylized zero.

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

Op-art architecture designed for happiness.

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

A neo-Gothic church built to thank God for saving the Emperor of Austria from an assassination.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

The beautiful baroque library of the Hapsburg empire.

The final resting place for the remains of 143 Habsburg royalty.

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

The palace window through which Protestant nobles flung two Catholic regents, thus sparking the Thirty Years' War.

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

The first museum in the world devoted to sexual gadgetry.

Macabre astrological automaton clock dating to the late 1400s.

A Jenga-style cylindrical tower of books that appears to go on forever.