A visit to Margam Country Park, about 40 kilometres west of Cardiff, is like stepping back to another era.

The lower grounds of the estate are scattered within the ruins of an 879-year-old abbey, once ravaged by the bubonic plague, while the more recently built 19th century Margam Castle sits at a higher vantage point, with views out across Port Talbot.

But a chance discovery in an adjacent field has uncovered a significant monument dating back to the Roman empire.

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"We are looking, I think without a shadow of a doubt, at a major Roman villa structure, potentially the largest in Wales and something that really is unknown in this part of the world," Swansea University Associate Professor Alexander Langlands.

It was discovered by chance, when a team of geophysical surveyors, commissioned by Langlands, proceeded to scan an unassuming area of the park after concluding their work on the abbey grounds.

"They said, 'I think you might want to come over, we've found something'," he said.

"As soon as I saw it, I thought 'Wow, that's impressive'."

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The exact location of the site within the park's grounds is being kept confidential to protect it from treasure hunters.

It is sitting about half to 1.8 metres below the surface, spanning out across an area of about 500 square metres.

Scans have detected portions of walls and the foundations of several structures including the villa and a basilica-like structure, believed to be more than 1600 years old.

Langlands said the discovery suggested the Romano-British people were living more peacefully and prosperously in this area than previously thought.

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"This find changes the narrative I think for south Wales and for western Britain more generally," he said.

"Often we talk about Wales as being a sort of 'edge of empire', a 'frontier zone' prone to instability and raiding from the west.

"But actually, to have something this fancy – something that would not be out of place in somewhere like Somerset or Gloucestershire – suggests that you've really got a civilised and peaceful way of life all the way here in West Glamorgan.

"To find one this size is really exceptional."

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The 'Pompeii of Port Talbot'

Researchers are hoping there may be other artefacts waiting to be discovered at the site like coins, pottery or even mosaics that would explain more about the former inhabitants of what was once known as Britannia.

They are hoping to be granted national funding to begin meticulous excavation works.

Councillor Cen Phillips from Neath Port Talbot Council said the site would likely draw international tourists and had already been given the nickname "Pompeii of Port Talbot".

"We already have so much heritage just in the park, from the Bronze Age right through to the 19th Century industrialists and their tremendous mansion," he said.

"To be able to add this missing link to the story is going to be huge for our communities."

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