The Dordogne is a river in south-central and southwest France, shown here in Périgord, near Castelnaud-la-Chapelle. It flows from Puy de Sancy generally west about 500 kilometres (310 mi) through the Limousin and Périgord regions before flowing into the Gironde in the north of the city of Bordeaux. The Dordogne and its watershed have been designated a biosphere reserve by UNESCO.Photograph: Luc Viatour