 Of the entire route, about are underground, while the rest is located in the open air.Initially, the planned termini were Pantano (a "frazione" of the "comune" of Monte Compatri) in the east and Clodio-Mazzini in the north, but in March 2007, a northward extension along the Via Cassia was announced, with nine more stations to Grottarossa.A depot has been built at Graniti.