Cagliari is an Italian municipality and the capital of the island of Sardinia, an Autonomous Region of Italy. Cagliari's Sardinian name Casteddu literally means castle. It has nearly 150,000 inhabitants, while its metropolitan area has more than 480,000 inhabitants.An ancient city with a long history, Cagliari has seen the rule of several civilizations. Under the buildings of the modern city there is a continuous stratification of human settlements of about five thousand years, from the Neolithic to today. There are some domus de janas, very damaged by cave activity, a large Carthaginian era necropolis, a Roman era amphitheater, a Byzantine basilica, two Pisan-era towers, a strong system of fortification that made the town the core of the Spanish Habsburg imperial power in the western Mediterranean sea. Its natural resources have always been its sheltered harbor, the oft-powerfully fortified hill of Monti Castru, the modern Casteddu, the salt from its lagoons, and, from inland, the Campidanian plain wheat and the Iglesiente mines.It was the capital of the Kingdom of Sardinia from 1324 to 1848, when Turin became the formal capital of the kingdom . Today the city is a regional cultural, educational, political and artistic centre, known for its diverse Art Nouveau architecture and several monuments., and Sardinia's economic and industrial hub, having one of the biggest ports in the Mediterranean sea, an international airport, and the 106th highest income rate in Italy, comparable to that of several Northern cities.It is also the seat of the University of Cagliari from 1607 and the Primate Roman Catholic archdiocese of Sardinia, from the 5th century AD.