The three largest cities are Milano, Napoli and Roma. Milano has an ancient history--it was the capital of the Cisalpine Gauls more than 2000 years ago--but its renewed prominence as a banking center of the nation's industrialized north has developed in recent centuries. Napoli is also ancient and sits beneath the active volcano, Vesuvio (Vesuvius). Roma, already nicknamed the eternal city in classical times, is the current national capital and was once capital of an empire embracing the entire Mediterranean Sea and more.

Large cities

Other cities of historical note

Other cities of note:

Bari (population of 316 thousand³) has a nearby airport that is one of the nation's busiest.⁴

Crotone (population of 62 thousand⁵), back when it was known as Κρότων (Króton), was where Pythagoras (6th century BCE) established his mathematical-religious school. People at that school were among those who independently discovered the Pythagorean Theorem.⁶

Footnotes

1. In millions. Of the metropolitan area if the center city; otherwise of the city proper.
2. 2012 figure from world-gazetteer.com, accessed February 6, 2013.
3. 2011 figure from https://en.wikipedia.org/wiki/List_of_cities_in_Italy, accessed February 16, 2017.
4. https://en.wikipedia.org/wiki/List_of_the_busiest_airports_in_Italy, accessed February 16, 2071. My criterion for inclusion: above 3 million total passengers.
5. 2011 figure from https://en.wikipedia.org/wiki/List_of_cities_in_Italy, accessed January 8, 2018.
6. See his biographical note in John Stillwell, Mathematics and its History (2nd ed., Springer, 2002).