The Dordogne is a river in south-central and southwest France. It is 483.1 km long. The Dordogne and its watershed were designated Biosphere Reserve by UNESCO on 11 July 2012. The river rises on the flanks of the Puy de Sancy at 1,885 metres above sea level in the mountains of Auvergne, from the confluence of two small torrents above the town …The Dordogne is a river in south-central and southwest France. It is 483.1 km long. The Dordogne and its watershed were designated Biosphere Reserve by UNESCO on 11 July 2012. The river rises on the flanks of the Puy de Sancy at 1,885 metres above sea level in the mountains of Auvergne, from the confluence of two small torrents above the town of Le Mont-Dore: the Dore and the Dogne. It flows generally west nearly 500 kilometres through the Limousin and Périgord regions before flowing into the Gironde, its common estuary with the Garonne, at the Bec d'Ambès, north of the city of Bordeaux.