As a visitor to Rome, you are most likely to roam around and stay in one of the rioni of the centro storico (historic center). The historic center of Rome roughly corresponds to the walled city; the Aurelian Walls were built between 271 and 275 AD to encompass all seven hills of Rome plus the Campus Martius and, on the right bank of the Tiber river, the Trastevere district. 

Since its origins, Rome has been divided into “regiones,” today’s rioni; so when we talk about the rioni of Rome, we are referring to the city’s central neighborhoods. The rioni form part of Municipio I, an administrative division of the city. (There are 15 Municipalities in Rome and each of them is divided into districts.)