World war 1

During World war 1, France built a fake Paris to fool Germany.

During World War I, the French created a dummy version of Paris to the city’s immediate north. The plan was to fool German planes into thinking the Potemkin city was the real thing, thus leaving the City of Lights untouched by bombs.
Fortunately, the plan was never put to the test. The war ended before the fake city was finished. Both the real Paris and the fake one escaped significant damage.The fake version has long since disappeared, though photos of it remain.