It consists of a part of the Metropolitan City of Rome Capital (formerly known as the Province of Rome) and a single comune, Aprilia, in the neighbouring Province of Latina.
Both provinces are part of the region of Lazio.
The metropolitan area does not have any administrative designation or function unlike the Metropolitan City of Rome Capital.
[3] All are within the Metropolitan City of Rome Capital except Aprilia in the Province of Latina.
The most important of these by population are: Guidonia Montecelio, Aprilia, Fiumicino, Tivoli, Ciampino, and Velletri, as shown in the table below.