The find was made during excavations of a domus, a private town house, in block (insula) 10 of the Regio IX area of Pompeii.

Experts said the spa, which is connected to a banquet hall, is the largest and most sophisticated private thermal baths found at a Pompeian domus.

The few other examples of such baths include those at the House of Julia Felix, the House of the Labyrinth and the Villa of Diomedes.

The bathhouse was found with a haul of artifacts including personal jewellery, said site director Gabriel Zuchtriegel.

“It’s a once in a lifetime discovery,” Zuchtriegel stated.

“Everything was functional to putting on a show, whose focus was the owner himself.”

“The excavation of the rooms in question, and in particular of the peristyle,” added the director of the works, Anna Onesti, “took place thanks to an innovative method of execution, which made it possible to reach the floor level avoiding the dismantling of the unstable architectural elements of the colonnade.”

Archaeologists said the direct connection of the thermal spaces to the large convivial hall (the so-called black hall, already discovered and made known a few months ago), suggests how the Roman house lent itself to being a real stage for the celebration of sumptuous banquets, which in the society of the time had a function not limited to what today we would define as “private” in the strict sense.

On the contrary, they were precious occasions for the owner to ensure the electoral consensus of his guests, to promote the candidacy of friends or relatives, or simply to affirm his social status.

The baths, composed of a calidarium, tepidarium, frigidarium (hot, warm and cold room) and changing room (apodyterium), could accommodate up to thirty people judging by the benches present in the latter room.

The archaeologists said the cold room is very impressive, composed of a peristyle, or a porticoed courtyard measuring 10 x 10 meters, at the centre of which is a large pool.

The newly-discovered private bathhouse in Pompeii. (Photo: AAP)

The choice to locate the complex near the large triclinium (banquet hall) refers to and meets an interpretation in Petronius’s famed satirical work the Satyricon, in which the rich freedman Trimalchio celebrates his famous lavish dinner, set in a Campanian city of the 1st century AD and therefore culturally not far from the reality of Pompeii before the eruption of 79 AD.

Before going to the banquet, the protagonists of the book, including Trimalchio, go to a balneum (bath).

The entire domus occupied the southern part of insula 10 and must have belonged to an important figure in local society, experts said.

The walls decorated in the second and third Styles of Roman wall painting demonstrate that it had an important history behind it.

Certainly, archaeologists said, whoever owned this home must have belonged to the city’s elite in its last decades of life and therefore felt the need to set up a space in their own home to host numerous people, to whom they could offer rich banquets and the opportunity to bathe and relax in the thermal baths.

The use of a temporary support structure allowed the entire colonnade to be excavated, leaving all the wall portions in place, and will remain to protect the entablature system (the horizontal structure supported by the columns) until a new, future, architectural and structural restoration project, also serving as support for its execution.

The main entrance to the domus was to the south.

An atrium was probably located here, from which one reached a large peristyle (colonnaded garden) that occupies almost the entire width of the block and of which the upper parts of the corner columns, not yet excavated, can be glimpsed.

On one side of the peristyle there was a series of rooms.

From west to east the property composes of: a large oecus (living room) decorated in the second style, a corridor, a small room decorated in the fourth style and a Corinthian oecus, surrounded by at least 12 columns on three sides with a second style megalographia which is currently still being excavated and of which the first results were presented in December: a frieze with still life compositions representing game and fish products.

ANSA