Marseille ( mar-SAY, French: [maʁsɛj] (listen), locally [maχˈsɛjə] (listen); also spelled in English as Marseilles; Occitan: Marselha [maʀˈsejɔ, -ˈsijɔ]) is the prefecture of the Bouches-du-Rhône department and Provence-Alpes-Côte d'Azur region, France. Situated in the Provence historical province, it is located on the coast of the Gulf of Lion, part of the Mediterranean Sea, near the mouth of the Rhône. Marseille is the second-largest city in France, covering an area of 241 km2 (93 sq mi); it had a population of 870,018 in 2016. Its metropolitan area, which extends over 3,174 km2 (1,225 sq mi), is the third-largest in France after those of Paris and Lyon, with a population of 1,760,653 as of 2017, or 3,100,329 (2019) by the broader Eurostat definition of metropolitan region. Its inhabitants are called Marseillais.

Founded around 600 BC by Greek settlers from Phocaea, Marseille is the oldest city of France, as well as one of Europe's oldest continuously inhabited settlements. It was known to the ancient Greeks as Massalia (Greek: Μασσαλία, romanized: Massalía) and to Romans as Massilia. Marseille has been a trading port since ancient times. In particular, it experienced a considerable commercial boom during the colonial period and especially during the 19th century, becoming a prosperous industrial and trading city. Nowadays the Old Port still lies at the heart of the city where the manufacturing of soap, its famous savon de Marseille, began some 6 centuries ago. Overlooking the port is the Basilica of Notre-Dame-de-la-Garde or "Bonne-mère" for the people of Marseille, a Romano-Byzantine church and the symbol of the city. Inherited from this past, the Grand Port Maritime de Marseille (GPMM) and the maritime economy are major poles of regional and national activity and Marseille remains the first French port, the second Mediterranean port and the fifth European port. Since its origins, Marseille's openness to the Mediterranean Sea has made it a cosmopolitan city marked by cultural and economic exchanges with Southern Europe, the Middle East, North Africa and Asia. In Europe, the city has the third largest Jewish community after London and Paris.In the 1990s, the Euroméditerranée project for economic development and urban renewal was launched. New infrastructures and renovations were carried out in the 2000s and 2010s: the tramway, the renovation of the Hôtel-Dieu into a luxury hotel, the expansion of the Velodrome Stadium, the CMA CGM Tower, as well as other quayside museums such as the Museum of Civilisations of Europe and the Mediterranean (MuCEM). As a result, Marseille now has the most museums in France after Paris. The city was named European Capital of Culture in 2013 and European Capital of Sport in 2017. Additionally, Marseille hosted matches at the 1998 World Cup and Euro 2016. It is also home to several higher education institutions in the region, including the University of Aix-Marseille.