Naples ( NAY-pəlz; Italian: Napoli [ˈnaːpoli] ; Neapolitan: Napule [ˈnɑːpulə]) is the regional capital of Campania and the third-largest city of Italy, after Rome and Milan, with a population of 908,082 within the city's administrative limits as of 2025, while its province-level municipality is the third most populous metropolitan city in Italy with a population of 2,958,410 residents, and the eighth most populous in the European Union. Its metropolitan area stretches beyond the boundaries of the city wall for approximately 30 kilometres (20 miles). Naples also plays a key role in international diplomacy, since it is home to NATO's Allied Joint Force Command Naples and the Parliamentary Assembly of the Mediterranean.

Founded by Greeks in the first millennium BC, Naples is one of the oldest continuously inhabited urban areas in the world. In the eighth century BC, a colony known as Parthenope (Ancient Greek: Παρθενόπη) was established on the Pizzofalcone hill. In the sixth century BC, it was refounded as Neápolis. The city was an important part of Magna Graecia, played a major role in the merging of Greek and Roman society, and was a significant cultural centre under the Romans.

Naples served as the capital of the Duchy of Naples (661–1139), subsequently as the capital of the Kingdom of Naples (1282–1816), and finally as the capital of the Kingdom of the Two Sicilies — until the unification of Italy in 1861. Naples is also considered a capital of the Baroque, beginning with the artist Caravaggio's career in the 17th century and the artistic revolution he inspired. It was also an important centre of humanism and Enlightenment. The city has long been a global point of reference for classical music and opera through the Neapolitan School. Between 1925 and 1936, Naples was expanded and upgraded by the Fascist regime. During the later years of World War II, it sustained severe damage from Allied bombing as they invaded the peninsula. The city underwent extensive reconstruction work after the war.

Since the late 20th century, Naples has had significant economic growth, helped by the construction of the Centro Direzionale business district and an advanced transportation network, which includes the Alta Velocità high-speed rail link to Rome and Salerno and an expanded subway network. Naples is the third-largest urban economy in Italy by GDP, after Milan and Rome. The Port of Naples is one of the most important in Europe.

Naples' historic city centre has been designated as a UNESCO World Heritage Site. A wide range of culturally and historically significant sites are nearby, including the Palace of Caserta and the Roman ruins of Pompeii and Herculaneum. Naples is undoubtedly one of the world's cities with the highest density of cultural, artistic, and monumental resources, described by the BBC as "the Italian city with too much history to handle."