It is the second most populated city in Sicily after Palermo, and one of the fifteen metropolitan cities in Italy. The urban area exceeds by far the city borders, and its population is composed of 637.587 people, while those living in the metropolitan area are 765.623. It is the tenth biggest city in Italy for its population and the Italian most populated city that is not a regional capital.
Founded in 729 B.C. by Chalcis settlers, its millenary history has been characterised by several dominations whose remains today enrich its artistic, architectural and cultural heritage. Under the Aragonese dinasty it was capital of the Kingdom of Sicily.
Over its history it has suffered several times volcanic eruptions (the biggest was in 1669) and earthquakes (the most catastrophic ones were in 1169 and 1693).
Its baroque city centre has been declared by UNESCO World Heritage, together with seven towns in Val di Noto (Caltagirone, Militello in Val di Catania, Modica, Noto, Palazzolo Acreide, Ragusa and Scicli), in 2002.