Imagine Paris in 1917. The city is on high alert, dangerously close to the front lines as World War I engulfs Europe. The Germans have become increasingly aggressive, sending silent, stealthy zeppelins and heavy duty airplanes across the continent to bomb the civilian cities of their enemies, particularly during the night.

Parisians watch as their neighbor to the north faces a constant barrage (in the end, family ties weren’t enough to prevent Kaiser Wilhelm II of Germany from bombing his first cousin, King George V of England). They have withstood attacks of their own, preparing for the raids by stacking up sandbags or taping up the windows of small shops, often creating designs that are truly works of art. (This is Paris, after all, and war is no excuse for not looking your best.)

The Parisians faced the dangers bravely; one 2016 account of a zeppelin raid that ultimate delivered 10 bombs reports that, when the bombers were first spotted and civilians urged to take cover, “Instead of dispersing, the Parisians who were in the main arteries were grouped and, taunting the danger, launched insults and threats towards the firmament.”

But despite these (questionable) acts of heroism, the bombs and threats of increased attacks were troubling. What could Paris do to protect itself?

At the beginning of 1917, a wild idea was floated. Why not build a replica of Paris just outside of the city and fool German bombers into dropping their destructive loads where only the decoys made of wood and fabric could be harmed.

At the time, aerial bombardment was an imprecise, DIY affair. This was before planes were equipped with radar, so pilots had to fly purely by sight. When they spotted what they believed to be their target, the bombs would be chucked out one-by-one and onto the unsuspecting population below.

Given the high opportunity for human error in this arrangement, Fernand Jacopozzi, an Italian engineer who helped architect the grand scheme to duplicate Paris, thought it would be easy to divert these German bombers with some crafty visual deception. The city officials quickly got on board.

The plan ultimately called for the construction of three separate “sham” neighborhoods just outside of the city. The first would be to the northeast of the city and would replicate a train hub; the second would be 11 miles to the northwest of the city, on a bend in the River Seine that was similar to that which went through Paris, and it would be a reproduction of the city center complete with iconic monuments; and the third would be directly to the east and would be a faux industrial zone with factories and other indications of wartime production.

A map drawn at the time points out the original Parisian neighborhoods that were to be copied, and where their facsimiles would be situated on the outskirts of town, close enough that they would convince the bombers that they were authentic, but far enough away that they would protect the city.

"Fake cities had limited utility, of course, but the idea did have its place. Even in the extraordinary history of deception, sham Paris was extraordinary,” John Ptak, a bookstore owner who discovered a copy of the original map of the decoy city in an old issue of the Illustrated London News, told CityLab.

It was to be a monumental undertaking that would not only attempt to replicate one of the largest, most well known cities in the world, but would also attempt to recreate such stunning achievements as the Gare du Nord, Arc de Triomphe, and Champs-Élysées.

The plans called for a combination of the cobbled together and the precise. Most of the structures were to be made out of plastic, wood, and cloth, convincing reproductions from the air, not so much from land.

But the streets were painstakingly laid out, including the inclusion of street lamps, artists were called in to paint the fake neighborhoods, adding a coat of translucent paint on roofs as a stand in for dirty glass skylights, and the wooden train moved along a track as if it were real. (An article in La Vie du Rail in 1968 revealed that the team who developed the movement capability of the train was entirely made of women).

But the most important piece of the puzzle was the lighting. As Germans increasingly began to make their raids at night in order to avoid anti-aircraft missiles, the lights of the city were their most important guideposts.

Jacopozzi’s idea was to impose a complete blackout on the city of Paris at night, blanketing the life of the city in total darkness. In the decoy neighborhoods, precise lighting would be engineered to simulate a city that was trying to snuff out its candle, so to speak, but that hadn’t fully succeeded.

Experimenting with multi-colored lights, Jacopozzi recreated the effect of the soft glow of lights peeping out from behind heavy drapes, the illumination given off by the interior of a moving train, and even the smoke produced by working furnaces.

One report even suggests that the lighting crew would test the effectiveness of their work by observing it from the third story of the Eiffel Tower to make sure they had gotten everything just right.

In the end, only parts of the decoy city were ever built, including a fake running train and some factory buildings. In 1918, before the project could be completed, the war came to an end and the government quickly moved to dismantle their secret project and suppress all information concerning it’s existence.

While this might have been one of the most ambitious decoy projects conceived, it was by no means the only one. During WWII, the British regularly used decoy villages that they kept burning—called Starfish cities—to try to distract and fool the Germans. The Americans took a different approach when they built fake cities over a Lockheed factory in Burbank and a Boeing factory in Seattle to try to disguise these instruments of war as innocent sites of civilian life.

More recently, North Korea has taken things a step further by building a decoy city of another sort. Within sight of their neighbors to the south, the North Koreans have constructed an entire empty city to try to maintain the facade of progress and industry.

But before the North Koreans started faking their way to success, there were the Parisians, who heckled their bombers from the ground while they stealthily constructed a sham city just miles away. In the end, Fake Paris may not have diverted a single bomber, but it remains an intriguing piece of history, one that had implications of a different sort on the future of the place it was trying to save.

This wartime venture was not Jacopozzi’s last inventive foray into illuminating the City of Lights; after creating the precise lighting of a decoy town, he went on to to brighten the actual wonders of Paris. Throughout the Roaring Twenties, Jacopozzi worked to light up some of the best known monuments ranging from the Eiffel Tower to the Arc de Triomphe.

“First he conceived the lights of wartime, a fake Paris, lost in a pseudo blackout, and then later the illuminations of a festive city,” Xavier Boissel, author of an essay on the decoy city said in an interview. “In both cases it is the city itself that is obscured, first by its military double, and then by its festive double, as paradoxically the over-exposure of the twenties helped transform Paris into a shadowy city.”