Haussmann's renovation of Paris was a vast public works program commissioned by Emperor Napoléon III and directed by his prefect of the Seine, Georges-Eugène Haussmann, between 1853 and 1870. It included the demolition of medieval neighborhoods that were deemed overcrowded and unhealthy by officials at the time; the building of wide avenues; new parks and squares; the annexation of the suburbs surrounding Paris; and the construction of new sewers, fountains and aqueducts. Haussmann's work met with fierce opposition, and he was finally dismissed by Napoleon III in 1870; but work on his projects continued until 1927. The street plan and distinctive appearance of the center of Paris today is largely the result of Haussmann's renovation.
In the middle of the nineteenth century, the center of Paris was overcrowded, dark, dangerous, and unhealthy. In 1845 the French social reformer Victor Considerant wrote: "Paris is an immense workshop of putrefaction, where misery, pestilence and sickness work in concert, where sunlight and air rarely penetrate. Paris is a terrible place where plants shrivel and perish, and where, of seven small infants, four die during the course of the year." The street plan on the Île de la Cité and in the neighborhood called the "quartier des Arcis", between the Louvre and the "Hôtel de Ville" (City Hall), had changed little since the Middle Ages. The population density in these neighborhoods was extremely high, compared with the rest of Paris; in the neighborhood of the Champs-Élysées, population density was estimated at 5380/km ²; in the neighborhoods of Arcis and Saint-Avoye, in the present Third Arrondissement, there was one inhabitant for every three square meters. In 1840, a doctor described one building in the Île de la Cité where a single room five meters square on the fourth floor was occupied by twenty-three people, both adults and children. In these conditions, disease spread very quickly. Cholera epidemics ravaged the city in 1832 and 1848. In the epidemic of 1848, five percent of the inhabitants of these two neighborhoods died.
Traffic circulation was another major problem. The widest streets in these two neighborhoods were only five meters wide; the narrowest were only one or two meters wide. Wagons, carriages and carts could barely move through the streets.
The center of the city was also a cradle of discontent and revolution; between 1830 and 1848, seven armed uprisings and revolts had broken out in the centre of Paris, particularly along the Faubourg Saint-Antoine, around the Hôtel de Ville, and around Montagne Sainte-Geneviève on the left bank. The residents of these neighborhoods had taken up paving stones and blocked the narrow streets with barricades, and had to be dislodged by the army.