48.8352, 2.2409
Boulogne-Billancourt (French pronunciation: [bulɔɲ bijɑ̃kuʁ]; often colloquially called simply Boulogne, until 1924 Boulogne-sur-Seine, [bulɔɲ syʁ sɛn]) is a wealthy and prestigious commune in the western suburbs of Paris, France, located 8.2 km (5 mi) from the centre of Paris. It is a subprefecture of the Hauts-de-Seine department and thus the seat of the larger arrondissement of Boulogne-Billancourt. It is also part of the Métropole du Grand Paris. Boulogne-Billancourt includes one island in the Seine: Île Seguin. With a population of 121,334 as of 2018, it is the most populous commune in Hauts-de-Seine and most populous suburb of Paris, as well as one of the most densely populated municipalities in Europe.Boulogne-Billancourt is one of the wealthiest regions in the Parisian area and in France. Formerly an important industrial site, it has successfully reconverted into business services and is now home to major communication companies headquartered in the Val de Seine business district.