Messina is a province in the autonomous island region of Sicily in Italy. Its capital is the city of Messina. The province included the Aeolian Islands, all part of the comune of Lipari (with the exception of Salina). The territory is largely mountainous, with the exception of alluvial plain at the mouths of the various rivers. The largest plain is that in the area between Milazzo and Barcellona Pozzo di Gotto, which, together with Messina, form a metropolitan area of some 500,000 inhabitants, one of the largest in southern Italy. Much of the population is concentrated in the coastal area, after the hill towns have been largely abandoned from the 19th century. The main mountain ridges are the Peloritani, up to 1,300 metres in elevation, and the Nebrodi, up to 1,900 metres, which are included in a Regional Natural Reserve. Rivers of the province include the Alcantara and the Pollina, which forms the border with the province of Palermo to the west.