Theft, cobblestone roads and taxi drivers.
Unemployment is extremely high - therefore so is theft - especially vehicles with foreign number plates (tags) ... beware!
Also, don't hang your jacket over the back of your chair in public places, keep it where you can see it.
Some of the main roads in downtown Naples are paved with uneven cobblestones. Very uneven! When on 2 wheels you quickly learn to fly. Don't ask me how I know.

All taxi drivers think they are in Ferraris or Lamborghinis ... and drive (race) accordingly (totally ignoring your existence).
Enjoy!