The Iron Gates is a gorge on the river Danube. It forms part of the boundary between Serbia (to the south) and Romania (north). In the broad sense it encompasses a route of 134 km (83 mi); in the narrow sense it only encompasses the last barrier on this route, just beyond the Romanian city of Orsova, that contains two hydroelectric dams, with two power stations, Iron Gate I Hydroelectric Power Station and Iron Gate II Hydroelectric Power Station. At this point in the Danube, the river separates the southern Carpathian Mountains from the northwestern foothills of the Balkan Mountains. The Romanian side of the gorge constitutes the Iron Gates natural park, whereas the Serbian part constitutes the Ðerdap national park. Archaeologists have named the Iron Gates mesolithic culture, of the central Danube region circa 13,000 to 5,000 years ago, after the gorge.