Alsace
There is controversy around the recognition of the Alsacian flag. The authentic historical flag is the Rot-un-Wiss ; Red and White are commonly found on the coat of arms of Alsacian cities (Strasbourg, Mulhouse, Sélestat...) and of many Swiss cites, especially in Basel's region. The German region Hesse uses a flag similar to the Rot-un-Wiss. As it underlines the Germanic roots of the region, it was replaced in 1949 by a new "Union jack-like" flag representing the union of the two déprtements. It has, however, no real historical relevance. It has been since replaced again by a slightly different one, also representing the two départements. With the purpose of "Frenchizing" the region, the Rot-un-Wiss has not been recognized by Paris. Some overzealous statesmen have called it a Nazi invention - while its origins date back to the XIth century and the Red and White banner of Gérard de Lorraine (aka. d'Alsace). The Rot-un-Wiss flag is still known as the real historical emblem of the region by most of the population and the departments' parliaments and has been widely used during protests against the creation of a new "super-region" gathering Champagne-Ardennes, Lorraine and Alsace, namely on Colmar's statue of liberty.

Q: Which French city did not recognize the Rot-un-Wiss flag?
Paris