Île de la Cité French pronunciation: ​[il də la site] is an island in the Seine river in the center of Paris, France. It was historically significant as the home of early Parisii settlers and later as the site of key monuments such as Notre-Dame de Paris, Sainte-Chapelle, and the Hôtel-Dieu. The island remains a vital administrative center, with institutions like the Palais de Justice and the Préfecture de Police.