The Île de la Cité can appear to be just another timeless part of Paris, untouched for centuries, to be preserved as it is and has always been. In reality, it is a relatively recently remodeled space, one of the least successful of the undertakings of George-Eugène Haussmann while he was Prefect of the Seine. It is, I believe, one of Paris’s major twenty-first century urban planning challenges, one that will play a critical role in signaling what kind of city Paris is to become.