48°51′06″N 2°21′23″E / 48.85167°N 2.35639°E
Île Saint-Louis (French: [il sɛ̃ lwi]), eleven hectares (27 acres) in size, is one of two natural islands in the Seine river, in Paris, France (the other natural island is the Île de la Cité, where Notre-Dame de Paris is located). Île Saint-Louis is connected to the rest of Paris by four bridges to both banks of the river and to the Île de la Cité by the Pont Saint-Louis.
The Île de la Cité (French: [il d(ə) la site]; lit. "Island of the City") is one of two natural islands on the Seine River (alongside Île Saint-Louis) in central Paris. It spans 22.5 hectares (56 acres) of land. In the 4th century, it was the site of the fortress of the area governor for the Roman Empire. In 508, Clovis I, the first King of the Franks, established his palace on the island. In the 12th century, its importance as a religious centre increased with the building of Notre-Dame cathedral, and the castle chapel of Sainte-Chapelle. The city hospital, the Hôtel-Dieu, possibly the oldest continuously operating hospital in the world, is also based on the island. Nearby is the site of the city's oldest surviving bridge, the Pont Neuf.
Even with the departure of the French kings to the Louvre Palace across the right bank, and later to the Palace of Versailles, the island remained a centre of administration and law courts. In 1302, it hosted the first meeting of the Parlement of Paris in the old royal palace and was later the site of the trials of aristocrats during the French Revolution. Today, in addition to the prominent cathedral and other shrines, it is the home of the Préfecture de Police, the Palais de Justice, and the Tribunal de commerce de Paris. The Mémorial des Martyrs de la Déportation, a memorial to the 200,000 people deported from Vichy France to Nazi concentration camps during the Second World War, is located at the eastern end of the island. As of 2016, the island's population was 891.
The 4th arrondissement of Paris (IV arrondissement) is one of the twenty arrondissements of Paris, the capital city of France. In spoken French, this arrondissement is referred to as quatrième. Along with the 1st, 2nd and 3rd arrondissements, it is in the first sector of Paris, which maintains a single local government rather than four separate ones.
The arrondissement, also known as Hôtel-de-Ville, is situated on the right bank of the River Seine. It contains the Renaissance-era Paris City Hall, rebuilt between 1874 and 1882. It also contains the Renaissance square of Place des Vosges, the overtly modern Pompidou Centre, and the lively southern part of the medieval district of Le Marais, which today is known for being the gay district of Paris. (The quieter northern part of Le Marais is within the 3rd arrondissement). The eastern part of the Île de la Cité (including Notre-Dame de Paris) and all of the Île Saint-Louis are also included within the 4th arrondissement.