The Prefecture of Ioannina is one of the four prefectures of Ipiros. It is bordered by the prefectures of Kozani and Trikala to the east, Albania to the north, the prefecture of Thesprotia to the west and the prefectures of Arta and Preveza to the south. It has a total area of about 5,000 km2 and a population of 160,000 inhabitants. Its greatest part is dominated by mountain ranges, parts of which belong to the Pindos spine. The Pindos range forms the border between Ipiros, Macedonia and Thessaly. It starts with Mount Grammos on the border of Ipiros with Western Macedonia and Albania. Further south is Mount Smolikas, the second highest mountain in Greece. The range continues southward with Mount Gamila or Timfi. The southern Pindos range is after Metsovo and it includes Peristeri or Lakmos, and the Athamanika mountains. Among the mountain ranges lie small fertile plains, long and narrow valleys, and steep ravines, such as the Aoos gorge and the impressive Vikos ravine. The Ioannina basin, the ancient Ellopia, with its lake Pamvotida occupies the central segment of the prefecture. The Arachtos, Aoos, Voidomatis, Kalamas, Louros and Acherondas rivers, as well as many torrents flow through almost the entire Prefecture of Ioannina. The prefecture consists of four counties: the county of Dodoni - in the center of the prefecture - the seat of which is Ioannina, the county of Metsovo - at the east of the prefecture - the seat of which is Metsovo, the county of Pogoni - at the north-east part of the prefecture, the seat of which is Delvinaki.