Walking through these lively and endearing medieval streets, it seems almost incredible that they were once considered the enemy, to be demolished in haste – and not, it has to be added, by the German military, who had less than healthy designs on Paris at various times between 1870 and 1945. No, it was none other than the Emperor of France, Napoleon III, and his Prefect for the Seine, George-Eugène Haussmann – who died 125 years ago – who had districts like the Marais in their sights.