This towering church is home to a world-famous organ and a treasure trove of medieval art.

Some 80,000 Delft Blue tiles line the inside of this Amsterdam walkway.

An intersection between architecture, industrial construction, machine, and scientific instrument.

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

An imperial church bombed to ruins during WWII now stands as a jagged memorial.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

A narrow passage next to a cafe leads to a courtyard exploding with murals, tags, and paste-ups.

Tiny memorials honor individual victims of the Holocaust.

A unique subway station where pillars evoke ancient civilizations.

An enigmatic concrete structure in a lakeside Toronto park raises more questions than answers.

Named after one of Canada's greatest writers who lived out her days in this quaint neighborhood.

A touching tribute to the "Wonky Donkey."

The remains of a once-famous hotel that also acted as an artist colony.

One of the largest underground systems runs under Canada's largest urban center.

A collection of old neon signs from all over Poland line a secluded courtyard.

The silly symbol for an underground protest group is now scattered around the city.

A striking public sculpture representing the period of martial law in Communist Poland.

It’s a painted window that looks completely real, hiding on a building in the market square.

This windmill has been grinding pigments for traditional paints for more than 200 years.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

A hidden church in a hidden courtyard tells the story of the Miracle of Amsterdam.

Cat art as far as the eye can see.