began in August 2006, before the first construction sites opened in March 2007 on Piazza Roberto Malatesta, to construct Malatesta station. The Lodi station followed one month later. In May 2008, crews constructed two tunnel boring machines at Giardinetti, and two months later the old Rome-Pantano railway was truncated at Giardinetti to allow restructuring part of the old surface line, which forms a part of the new metro. This section, from Montecompatri-Pantano to Parco di Centocelle, opened in 2014. The section between Parco di Centocelle to Lodi opened on 29 June 2015, one further station opened in May 2018. The section of Line C further west is partly under construction and is due to open in 2024. Planning for an additional station at Piazza Venezia is currently in the planning phase and funding has been secured. Project planning for further extensions crossing the city centre was suspended in 2010. A shortened extension to Ottaviano is again under discussion. In 2009, during preliminary excavations for the station at Piazza Venezia workers found remains of what has been identified as emperor Hadrian's Athenaeum.
Route
Line C operates on of route, and serves 22 stations. Of the entire route, about are underground, while the rest is located in the open air. Initially, the planned termini were Pantano 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. Once construction is complete, the line will cross Line A not only at San Giovanni but also at Ottaviano, and Line B at Colosseo. At Pigneto, a new railway station is currently being constructed on the FL1 line. At the Colosseo stop a public museum was to be constructed in the station to display archaeological material that was excavated during construction, but the project has been scrapped due to the lack of funds. Instead, a portion of the ruins of the barracks used by the Praetorian Guard will be viewable through a large glass window. The initial plan featured a station at Largo di Torre Argentina in the city center. However, archaeological remains on the site were even more extensive than expected and the station was cancelled.
Extensions
The following extensions have been studied:
Northward and the Rome-Viterbo railway, which would be connected to the Metro line at Tor di Quinto; this extension would have five stations and would allow for interchange with the FL5 line at Vigna Clara and Tor di Quinto;
A southward extension of one station to Tor Vergata, where a secondary depot might be built;
A northward extension of the east branch from Teano to reach Ponte Mammolo allowing interchange with Line B, with five new stations. This extension would also meet FL2 at Togliatti.
Rolling stock
Line C is served by 30 AnsaldoBreda Driverless Metro convoys. The metro depot of Line C, the Deposito di Graniti, which extends over 21.7 hectare, is located between the station Graniti and the Eastern terminus Monte Compatri-Pantano. It additionally serves as the maintenance and control center of Line C.
