www.guardian.co.uk Archaeologists unveiled a 2,000-year-old burial ground discovered by chance inside the Vatican City.

The necropolis, which traces pagan Rome to the birth of Christianity, was discovered three years ago while excavations were being carried out for an underground garage to ease the Vatican's parking problems.

It contains more than 40 elaborately decorated mausoleums and 200 individual tombs. Headstones, including one that belonged to a slave of Nero, funerary urns and elaborately decorated frescoes and mosaic floors have also been uncovered on the site.

The historical importance of the find is being described as second only to the necropolis below St Peter's Basilica, which is believed to contain relics of St Peter, the first pope.

Giandomenico Spinola, director of the project, described the necropolis as being in an excellent condition because it had been protected by a landslide at the end of the second century. "We found the kind of things that have usually been lost in past excavations in Rome," he said.

Most of the tombs date from between the era of Augustus (23BC to 14AD) to that of Constantine (306-337).

The necropolis is unusual because the rich were buried alongside the poor. Next to tombs of middle-class Romans - one a tabellarius (letter carrier) and another a hortator (circus horse trainer) - are elaborately carved sarcophagi of Romans with more money. The headstone of a young nobleman called Publius Caesilius Victorinus indicated his love of hunting. The headstone of Nero's slave Alcimus reveals that his job included designing sets for the theatre at Pompeii.

Terracotta tubes inserted into graves through which mourning family would pour honey to nourish the dead have also been uncovered.

The necropolis is being restored as part of the Vatican Museum's 500th anniversary celebrations. The public will be able to visit from next week.