History. Founded by Greeks and inhabited by Romans, Naples was later a kingdom that passed between Austrian, French, and Spanish royal families. Fortunes waxed and waned with the changing royals, but the capital of southern Italy thrived under Angevin patronage in the 13th century, under the Aragonese during the Renaissance, and under Charles of Bourbon in the 1700s.
Safety. Naples has a reputation for petty crime, but that rep is (partly) unfair. Sightseeing and going out for the evening within the centro antico (old centre), Chiaia, Vomero, and along the Mergellina (the seafront) is safe—take the precautions you would take in any city. A more common danger is the traffic. Even on “pedestrian” streets in the centre, expect to meet a scooter or car at any moment. Hold little hands tight.
Food. Pizza is a Neapolitan invention, and you should also visit a traditional friggitoria (a fry shop) for a cheap snack on-the-go. Other traditional dishes pluck their ingredients straight from the sea—spaghetti alle vongole (with clams) is the classic primo.
Essential reading. Norman Lewis’ travelogue Naples ’44 describes the city as he found it during his time posted as an intelligence officer right after the Allied invasion of Italy. H. V. Morton’s A Traveller in Southern Italy has an evocative section on his time in Naples.