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

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

A statue in Budapest's Liberty Square honors the former U.S. president's efforts to end the Cold War.

A random tree outside a Budapest hotel has become a DIY shrine to the late singer.

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

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

A Nesting Doll of Churches.

Inside this building is another country within Rome, a sovereign entity without a physical territory.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

As can be expected from a centuries old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

Those who own or stay at this 500-year-old, allegedly cursed house often meet terrible fates.

This Roman statue is missing a limb from when the Venetians stole it from Constantinople during the Crusades.

Two stone columns flank the grand Venice square, but there were supposed to be three.

Go inside to really appreciate this 500-year-old technological masterpiece.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

Along the edge of this fountain are 365 smaller fountains that represent the days of the year.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

Some of the greatest minds in the history of Hungarian art and science converged in this café.

The medieval "Bearded Man" relief still serves as a clever flood warning marker.

A plaque marks the spot where the saint was shoved off the Charles Bridge and into the river.

A turn of the century building boasting some of the most beautiful art nouveau architecture in Prague.

Looming communist pillar with a Czech twist.

An existential riddle in the world's largest ancient castle.

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