Two hundred feet below the streets of Rome, a team of archaeologists has discovered 1,600 year old frescoes using laser beam technology.

The brightly coloured paintings, which date to around 360 AD were uncovered on the ceilings of two ancient Christian tombs in the labyrinthine Catacombs of St Domitilla. Hidden for centuries under layers of algae, smoke residue and calcium they were brought to the surface using 2mm laser beams.

Leader of the archaeological team, Barbara Mazzei, explained how advances in laser technology made it possible to safely unearth the frescoes. “The frequency of the 2mm laser beams can be adjusted to eliminate certain colours”, Mazzei said. “Different wavelengths and chromatic selection enabled us to burn away the black disfiguration without touching the colours beneath”.

Manually removing the grime without the use of lasers carried the risk of damaging the ancient paintings.

Used to house the families of rich Roman grain merchants, the crypts of the St Domitilla catacombs were forgotten after the fall of the Roman Empire. In the 16th century, an amateur archaeologist named Antonio Bosio who Mazzei regards as the “Christopher Columbus of the catacombs” rediscovered them. “We knew there were frescoes under there, and the lasers let us get to them”, she stated.

Working “millimetre by millimetre” Mazzei and her team discovered brilliantly coloured paintings of pagan symbols of the seasons and biblical scenes from the Old and New Testaments. They also exposed a cycle of frescoes depicting the state-controlled import and distribution of grain, which arrived in Rome via ship from the Mediterranean.

The paintings offer a valuable insight into the popularisation of Christianity among wealthy Romans in the 4th century AD as they shifted away from paganism, as well as the importance of the imperial grain trade and the prestige of the families who grew rich from it.