Faubourg is not French for "the district." It is a contraction of "faux bourg", French for "false town" and were used to designate smaller towns attached to larger towns or cities. A lot of these faubourgs were independent cities until they were attached to Paris and lost all independence around during the 17th and 18th century. A new outer wall was later erected around the city. These faubourgs, especially those on the East side, were usually blue collar, with a very active night life.
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The relationship between Douce, the young French singer, and Galapiat, the Fascist owner of the theater, is based on the relationship between singer Edith Piaf and French nightclub owner Louis Leplee (also depicted in the film La Vie en Rose (2007), a.k.a. "La Vie En Rose") In 1935, Leplee discovered Piaf as a young street singer in Paris. He managed her career until Leplee was shot to death in his apartment by French gangsters in April, 1936.