At first glance, the coin looks insignificant.

Peering intently, archaeologist Frank Giecco turns the coin over in his hand and grins broadly as the light picks out the worn image of a woman, seated inelegantly on a rock, her shield and spear discarded nearby, her body language dejected.

“It's Britannia,” says Frank.

“There was a rebellion in Roman Britain in 154AD but the Romans crushed it. This coin was an early example of Roman propaganda: it's one of the first images of Britannia, [the personification of Britain].”

The find is typical of the treasures which are being uncovered by archaeologists and volunteers working on the month-long dig at Carlisle Cricket Club's Edenside ground, a short walk from Stanwix.

Even beneath a grey sky, with a chilling drizzle, the excitement generated by the dig is almost palpable. Everywhere, there are dozens of enthusiasts working away, quietly exposing the secrets of a once forgotten Roman military bath-house.

It's hard to underestimate the significance of this chance find.

Stanwix was once home to ala Petriana, the elite 1,000 strong cavalry regiment whose soldiers ruthlessly guarded the Roman Empire's most northerly frontier.

For Frank and everybody else involved in the dig the real thrill of this project is the discovery of clues that tell that Roman story: artefacts that shed light on how the life of the Empire's most feared soldiers.

"We've found more than 350 small objects,” he says.

Among his personal favourites are the trinkets, showing that while these tough military men were obliged to remain bachelors during their service, women were nevertheless very much a part of their life.

A bronze hair pin, bone needles, and jewellery... these are just some of the artefacts revealing the regular presence of women.

Frank's stand-out artefact is a stunning ring – with a key attached. “It's literally a key-ring – probably for a jewellery box,” says Frank.

Of real historical significance are those items that have revealed the site's potential link with Rome's imperial leaders – particularly the second century Emperor Septimius Severus and his Syrian wife Julia Domna.

One of the earliest finds at the site – found by chance beneath two disused tennis courts – was a beautifully preserved inscription stone, paying fulsome tribute to the Empress.

She frequently joined her husband on overseas military campaigns.

“Carlisle wasn't regarded by the Romans as just a backwater,” says Frank.

“It was of great strategic importance. The bath-house may have been a project undertaken for her and the Emperor's visit to Carlisle.

“He died in York in 2011.

“We know that they came to the north of England to see building projects. A lot of items we have found here have the imperial stamp – items such as wall tiles; and there have been a lot of high-status finds.

“We've found painted wall plaster of the kind that the Romans used only in posh buildings. There are traces of fresco, with blues and reds - the kind of thing you normally would find in Roman villas; in high status buildings.”

The other early finds have included large sections of hypocaust – the Roman equivalent of underfloor heating and pipes for circulating hot air.

Take a tour with our 360-degree video:

360 image of the archaeological dig in Stanwix Carlisle on the site of a Roman Baths House - Spherical Image - RICOH THETA

With the dig about to finish, many of those who have got involved are keen to push the discoveries as far as they can.

Frank's colleague at the Carlisle office of Wardell Armstrong Archaeology Kevin Mounsey believes that the two digs so far undertaken have uncovered only 60 per cent of buildings that lay buried beneath the site.

“Military bath-houses tend to match the size of the fort they served,” he says. As he surveys the site, a wave of stinging rain splatters down.

Looking at the many volunteers – many crouched over fragments of stone with brushes or trowels in the quickening rain – Kevin pays tribute to them, remarking: “They come out in all weathers. We've even had people come up from Wigan.

“There's a real enthusiasm.”

The passion for discovery is infectious - and that's why so many volunteers have been inspired to join in.

Billy Forbes, 71, from Maryport, pauses from his digging. “I just love history,” he declares. “I've found a few coins, and some pottery. But it's the buildings. To think that they were created all those hundreds of years ago and they're still standing.”

Lynda Howard, 58, from Staveley, near Kendal, and her partner, took part in a Roman dig near Cockermouth. “We couldn't miss the chance to get involved in this one,” she says, beaming. “It's our heritage.

“There have been an amazing number of small finds. I found a bronze pin, and a bone hair pin. It's exciting.” Working nearby, her partner Mick Fairfield – an engineer – says: “I was struck by how precisely the little bone needle we found was made.”

John Mather, 63, from Thursby, says: “I'm fascinated by Roman history and anything to do with Hadrian's Wall. This is a great opportunity to give a little back to Carlisle and discover more of its heritage.

“From the day that news of this dig came out in early spring thanks to your paper it has created a real interest in the area.

“On Friday afternoon, as I was digging, I saw a fine, bright yellow glimmer. I thought: 'That's bone.' It had a little head one one side, and a sharp point on the other. You ask yourself what on earth was it doing in a military bath-house?

“An Australian who was here was absolutely ecstatic, because it was a link with life here 2,000 years ago.”

The second dig is being funded jointly by Carlisle City Council, and Cumbrian construction tycoon Fred Story, owner of Story Contracting and Story Homes. The project is also being enthusiastically supported by Carlisle Cricket Club, who own the site.

The archaeology was uncovered during a routine exploratory dig commissioned by the club as part of preparation for the building of a new pavilion.