2,000-year-old military base discovered during works for Rome's Metro C.

The Italian culture ministry has unveiled an ancient Roman barracks, found during Metro C works in the S. Giovanni area of Rome in November, in what is described as one of the capital's most important archaeological finds in recent years.

The discovery of the second-century military base, which was used by Hadrian's Praetorian guards, was made during the construction of the Amba Aradam station as part of the city's third subway line.

Located nine metres underground, the 1,750-sqm imperial complex includes 39 rooms with ornate mosaic floors, a 100m-long hallway and a grave with 13 adult skeletons. Archaeologists have also discovered bronze coins and jewellery on the site.

Francesco Prosperetti, the superintendent for Rome’s archaeological heritage, said the “exceptional” find would not delay the construction of Amba Aradam station but would necessitate some modifications to the station's design.

The Metro C project has been beset with difficulties since it started in 1990, from massive funding overspends to lengthy bureaucratic delays and abandonment of planned stations caused by the discovery of archaeological remains underground.

The easternmost section of the driverless line opened in November 2014, with 15 stations from Pantano to Centocelle. The second section was launched in July 2015, from Centocelle to Lodi, going towards S. Giovanni, making a total of 21 stations over 18km.

Virginia Raggi, the current favourite to win Rome's upcoming mayoral race on 5 June, has made getting Metro C operational as far as the Colosseum part of her three-point transport plan.