Cagliari (Italian: [ˈkaʎʎari] ( listen); Sardinian: Casteddu; Latin: Caralis) 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 149.883 inhabitants, and 453.728 including its metropolitan area: Elmas, Assemini, Capoterra, Selargius, Sestu, Monserrato, Quartucciu, Quartu Sant'Elena and other 15 municipalities.

An ancient city with a long history, Cagliari has seen the rule of several civilizations. It was the capital of the Kingdom of Sardinia (which in 1861 became the Kingdom of Italy) from 1324 to 1848, when Turin, the mansion of the sovereigns, became the formal capital of the kingdom. Seat of the important University of Cagliari from 1607 and the Primate Roman Catholic archdiocese of Sardinia, from the 5th century AD, the city is an important regional cultural, educational, political and artistic centre, known for its diverse Art Nouveau architecture and several monuments. It is also Sardinia's economic and industrial hub, having one of the biggest ports in the Mediterranean sea, an international airport, and the 28th highest income rate in Italy, comparable to several Northern cities, such as Turin, Vicenza and Genoa. Under the buildings of the modern city there is a continuous stratification of human settlements of about five thousands years, from neolithic era to today. There are some Domus de janas, very ruined by cave activity, a great Carthaginian era necropolis, a great roman era amphitheater, a Byzantine basilica, two extraordinary Pisan-era towers, a formidable 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.