One of France's most celebrated monuments is the Arc de Triomphe. A network of broad boulevards, including the central Champs Élysées, radiate from the monument, enhancing its majestic presence. Few French would hesitate to elect this section of Paris as the architectural symbol of the nation's grandeur and mission in the world, or mission civilisatrice, as they used to call it. Several times a year, city authorities have the boulevards' bustling traffic detoured to make space for the most significant national events, from presidential ceremonies to the last relay of the Tour de France. This area of Paris was the Bonapartes' self-reward. In 1806 Napoleon I commissioned the construction of the monument as a grandiose symbol of his imperial rule. Fifty years later his nephew, Louis Napoleon, ordered the expansion of the boulevards to mark the birth of a Second Empire. Since both empires turned out to be rather short-lived, the Arc de Triomphe and the boulevards, with all their pomp and magnitude, could be seen as the ironic tribute to their sponsors' ephemeral glory, and perhaps to the vanity of modern France. On the stage of the Champs Élysées, the nation continued to play its internal strife and witnessed the humiliation of foreign invasion. Louis Napoleon had thought the broad boulevards, replacing an intricate network of medieval streets, would prevent Parisian revolutionaries from raising barricades again. But the Communards in 1870 still managed to wage their revolution on the Champs Élysées. Twice in less than a century, in 1871 and in 1940, German troops marched under the Arc de Triomphe, adding shame to irony for this emblem of la grande nation.