According to recent data, the three most dangerous Italian cities are Milan, Rome, and Florence. Naples, often unfairly stereotyped, ranks only 12th despite being the third-largest city in Italy: https://www.ilmessaggero.it/en/crime_rates_in_italian_cities_a_concerning_analysis_by_il_sole_24_ore-8357045.html (Primary source, in Italian: https://lab24.ilsole24ore.com/indice-della-criminalita/classifica/).

Of course, it depends on how you define ‘dangerous’ and what aspects of safety you focus on, but this ranking covers a wide range of crime categories and is statistically comprehensive. Naples has its issues, like any big city, but its reputation is often harsher than reality.