Metro Line C, Rome’s third underground line, provided for in the General Urban Development Plan and confirmed in the Sustainable Urban Mobility Plan approved on 13 December 2024 by the Metropolitan City of Roma Capitale, crosses the city from south-east to north-west, connecting distant urban areas and significantly expanding the existing underground network.

The line’s total route runs for approximately 29 km and counts 31 stations. It starts in the municipality of Monte Compatri, follows the route of the former Termini–Pantano railway line at surface level, then goes underground just before the Grande Raccordo Anulare ring-road. The line crosses the historic centre, Prati and Mazzini districts, to end at Farnesina district, after passing under the River Tiber three times. The system uses fully automated technology, with driverless trains and automatic doors separating the platforms from the tracks. Line C interchanges twice with Line A (at San Giovanni and Ottaviano stations), once with Line B (at Colosseo/Fori Imperiali station) and once with the regional railways (at Pigneto station).

The route is divided into several sections: T1, from Farnesina station to Mazzini station (excluding Mazzini station); T2, from Mazzini station to Colosseo/Fori Imperiali station (excluding Colosseo/Fori Imperiali station), currently under construction; T3, T4, T5, T6A and T7, from Colosseo/Fori Imperiali station to the Monte Compatri/Pantano terminus, plus the Graniti Depot/Workshop, already in service. This line C route division depends on the availability of funding and changes in the public procurement legislation.

The entire length of the T3 section, from the Colosseo/Fori Imperiali station to the San Giovanni station (excluded), is situated within an area that is unique in the world for its significant historical and monumental heritage; it covers a total distance of approximately 3 km and includes two stations, Colosseo/Fori Imperiali and Porta Metronia, two multi-purpose shafts, located in Piazza Celimontana and in the gardens on Via Sannio, respectively, and two line tunnels built almost entirely using a TBM, a tunnel boring machine or mechanical mole. The tunnels were excavated below the archaeological layer, at a depth of between approximately 30 and 60 metres.

The line became operational on 16 December 2025, following approximately 12 and a half years of construction work, which began in March 2013. Part of the work, including the multi-purpose shaft on Via Sannio and approximately 140 metres of tunnels leading to San Giovanni, had been completed ahead of schedule on 18 June 2021. This section was authorised for operation from 11 August 2022.

This early completion meant that trains arriving from Monte Compatri/Pantano could reverse direction beyond the San Giovanni station, which was the temporary terminus at the time, via a rail link near Via Sannio. This way, both platforms at the station could be used, allowing for better management of passenger flow.

With the opening of the T3 section, another railway junction was also added in the multi-purpose shaft at Piazza Celimontana. This structure also serves as an emergency access point for the Fire Brigade and contains a number of ventilation systems.

The two tunnels on the T3 section were excavated using a TBM, starting from the shaft on Via Sannio and proceeding towards the Colosseum; the tunnelling work, which began in March 2018, was completed in September 2020, ending beyond the boundary of the T3 section at the future Venezia station, which forms part of the subsequent T2 section (CIPE Resolution 76/2019).

The Colosseo/Fori Imperiali and Porta Metronia stations are two of the six ‘archaeological stations’ planned along Line C, along with San Giovanni (already operational), Venezia, Chiesa Nuova and Piazza Pia/Castel S. Angelo (under construction). The Colosseo/Fori Imperiali station is situated beneath Via dei Fori Imperiali in an area of great historical importance, adjacent to the Flavian Amphitheatre, the Basilica of Maxentius, the Temple of Venus and Rome, and the Villa Rivaldi complex. The new station is directly connected to the existing Colosseo station on Line B via an underground passageway that crosses over the Line B tunnel, allowing passengers to move between the two lines.

The station structure was built using the ‘top-down’ method, excavating from the top downwards within vertical reinforced concrete walls (‘diaphragms’) that contained the excavation. The station extends between the Colosseum and the area in front of the Basilica of Maxentius, covering a maximum length of 150 metres, with a width of 34 metres and a depth of 32 metres below street level. It is divided into four underground levels. The station can be accessed not only via the underground passageway for passengers coming from Line B, but also directly from the street via two access ramps on Via dei Fori Imperiali, on the Clivo di Acilio side and the Clivo di Venere Felice side.

Construction of the station involved the ancient Velia hill, much of which was levelled in the early 1930s to make way for the Via dei Fori Imperiali. Although these works compromised many of the pre-existing archaeological remains beneath the ground, preliminary surveys and excavations at the station and the Colosseum shaft – totalling 29,000 cubic metres of archaeological excavation – brought to light various structures. Consequently, under the direction of the Colosseum Archaeological Park (Ministry of Culture), two design changes had to be made during construction: one to the exhibition layout inside the station and the other to reposition the ancient walls discovered along the Clivo di Acilio. 

In order to exhibit the archaeological finds and tell the story of the area, museum spaces organised into five sections were created in the station. The first, on the concourse level, outside the turnstiles and therefore freely accessible, focuses on the changes that have taken place over the centuries in the area between the Colosseum and Piazza Venezia, illustrated with display cases and various multimedia techniques. The second, also on the concourse level, displays and illustrates some of the 28 wells discovered during the excavation, and dating from the Archaic and Republican periods. Continuing down to the mezzanine level, the third section reconstructs the ancient landscape of the Velia Hill, displaying, among other things, the masonry remains of a late Republican-era residence featuring a thermal bath and a laconicum. The fourth section revisits the theme of the wells, illustrating their function as ritual storage sites after the water supply had run dry. Finally, at the centre of the station building, the impressive system of stairs and escalators connecting the atrium to the mezzanine forms a sort of ‘Forum’ for the station, enclosed in a large ‘golden cage’.

The funding allocation for the Colosseo/Fori Imperiali station is part of the Economic Framework (Q.E.) totalling 946,071,902.86 euros for the Rome Metro – Line C, Section T3. The Economic Framework is funded in accordance with CIPE Resolution No. 127/2012 and the new funding from the Ministry of Infrastructure and Transport (MIT) as set out in Laws No. 234/2021, No. 197/2022 and No. 207/2024.