Thousands of narrow alleyways in an ancient medieval city make up what's believed to be the world's largest car-free urban zone.

This religious complex carved into a cliff is steeped in legends of miraculous stags and the Holy Grail.

French commune at the heart of conspiracies.

A Gothic cathedral created from volcanic rocks.

Lyon's "Wall of the Silk Weavers" is one of the largest murals in Europe.

According to a local legend, this old castle could only be built after a woman was immured in the walls.

Hundreds of thousands of concrete bunkers crowd Albania long after the fall of Communism.

In the heart of Tirana, this underground nuclear bunker has been transformed into a museum.

Once the fallout shelter of a dictator, this sprawling bunker is now a combined history museum and contemporary art gallery.

This abandoned prison was so notorious that its name has become a metaphor throughout Albania.

This demon atop the Notre-Dame de Paris looks utterly bored.

If you look closely at the oldest bridge in Paris, you might notice hundreds of ugly faces leering from its sides.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

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

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

Once the tallest building in the world, this abandoned church is now a monument to the destruction of WWII.

A restaurant and observation deck built in a unique broadcasting antenna.

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

At this faithfully preserved medina off the Moroccan tourist circuit you can walk through six centuries of history in one day.

One of the tallest waterfalls in Africa is also home to a population of monkeys who enjoy the waters and the occasional guest.

Traditional 11th-century outdoor tannery.

The largest madrasa in Morocco once housed more than 900 students within its exquisite walls.

World's largest film studio, where visitors tour the decaying sets that litter the harsh desert environment.