Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A rione (pl. rioni) is an Italian term used since the Middle Ages to name the districts of central Rome, according to the political divisions of that time. It comes from the Latin regio (pl. regiones, meaning region); during the Middle Ages the Latin word became rejones, from which rione. The rioni were established for the first time in the 4th century BC by Servius Tullius: they were only four and they were called regiones.