New Orleans, Louisiana. Saint Louis Cathedral (French: Cathédrale Saint-Louis, Roi de France), also known as the Basilica of St. Louis, King of France, is the seat of the Roman Catholic Archdiocese of New Orleans; it has the distinction of being the oldest continuously operating cathedral in the (as now constituted) United States. The first church on the site was built in 1718; the third, built in 1789, was raised to cathedral rank in 1793. The cathedral was expanded and largely rebuilt in 1850, with little of the 1789 structure remaining.

Saint Louis Cathedral is in the French Quarter of New Orleans, Louisiana, USA, on the Place John Paul II (French: Place Jean-Paul II), a promenaded section of Chartres Street (rue de Chartres) that stretches one block between St. Peter Street (rue Saint-Pierre) on the upriver boundary and St. Ann Street (rue Sainte-Anne) on the downriver boundary. It is located next to Jackson Square and facing the Mississippi River in the heart of New Orleans, situated between the historic buildings of the Cabildo and the Presbytère. It is one of the few Roman Catholic churches in the United States that fronts a major public square.