In the 19th century, Haussmann’s architecture transformed Paris. Under the Second Empire, Napoleon III wanted to revamp the old, narrow, and unhealthy centre of Paris. He commissioned Baron Haussmann to draw up a real urbanisation plan. As Prefect of the Seine, Haussmann had full powers. He razed entire districts and built nearly 40,000 ashlar buildings, all similar, never exceeding six stories. Elegant wrought-iron balconies were placed on the second and fifth floors. With wide tree-lined avenues, squares and parks, railway stations and an opera house, Paris grew from 12 to 20 arrondissements.