During World War I, to prevent the historic city from being destroyed by German bombs, the French built a dummy version of Paris just north of the city. The idea was to create a cheap, but realistic, version of Paris that would distract Germans from the real Paris and leave it unscathed.
The city had electric lights, replica buildings, a fake Champs-Elysés and even little details like dirty glass roofs on factories. The diversion was very plausible. Radar technology was still brand new at the time, and the German bomber planes were not very judicious with their targets.
Thankfully, neither the real Paris nor the fake one were victims of German bombs. The war ended before the fake city was finished. Photos of the city are also very difficult to find.