Pompeii, the ancient Roman city buried by ash and lava in AD 79, has unearthed a new treasure — a private bathhouse built 2,000 years ago, decorated with sumptuous mosaics and equipped with a series of hot, warm and cold rooms in the manner of a spa.

"We have here perhaps the largest thermal complex in a private house in Pompeii," said Gabriel Zuchtriegel, director of the Pompeii archaeological park. "The members of the ruling class of Pompeii set up enormous spaces in their homes to host banquets.   

"They had the function of creating consensus, promoting an election campaign, closing deals. It was an opportunity to show the wealth in which they lived and also to have a nice thermal treatment," he said.

The baths were unearthed in the so-called Regio IX, a large central area of Pompeii park still unexplored, where major archaeological excavations are revealing new aspects of Pompeians' daily life.

Recently, archaeologists working in the same area found a bakery, a laundry shop, two villas and the bones of three people who died during the volcanic eruption of Mount Vesuvius, which destroyed the ancient Roman cities of Pompeii and Herculaneum. 

At the time of the eruption, Pompeii was home to around 13,000 people. The remains lie around 23 kilometres southeast of Naples. 

Bath before banquet

Footage of the excavation site shows dusty walls decorated with red, black and yellow stripes, and a large rectangular basin, complete with what looks like curved stone steps or seats in the corner of the bath itself. 

Zuchtriegel said wealthy habitants of Pompeii often used first to take a bath and then have a banquet, so the private spa complex allowed them to do that inside the same house.

"There is room for about 30 people who could do the whole routine, and that could also be done in public baths. So there is the calidarium, a very warm environment and also a large tub with cold water," he said.