Seine-et-Marne (pronounced: [sɛn e maʁn]) is a French department, named after the Seine and Marne rivers, and located in the Île-de-France region.
Seine-et-Marne is one of the original 83 departments, created on 4 March 1790, during the French Revolution in application of the law of December 22, 1789. It had previously belonged to the former province of Île-de-France.
Seine-et-Marne forms a part of the Île-de-France region; the department covers 49% of the region's land area. It is bordered by Val-d'Oise, Seine-Saint-Denis, Val-de-Marne, Essonne to the West; Loiret and Yonne to the South; Aube and Marne to the East; and Aisne and Oise to the North.
The department has many natural reserves, notably Brie and Gâtinais.
Principal towns include: Chelles, Torcy, Pontault-Combault, Lagny-sur-Marne, Coulommiers, Champs-sur-Marne, Nemours, Meaux, Melun, Montereau-Fault-Yonne, Brie-Comte-Robert, Provins, Fontainebleau as well as the new towns of Marne-la-Vallée and Sénart.