A Roman road has been found by workers building a controversial £840m natural gas pipeline across Wales.
Richard Field on the Roman road found on the pipeline's route
The historic roadway was discovered in the Brecon Beacons, on the path of the 190-mile (320km) National Grid pipe from Milford Haven to Gloucestershire.
Neil Fairburn, archaeology project manager for National Grid, said the road was found as digging began, but the pipe would still have to cross it.
A local community councillor said he hoped the find would be looked after.
Mr Fairburn said the road, which he estimated as dating from the 1st Century AD, was in "a better condition than we would normally find a Roman road", but a 3m section of it would be lost.
"It was in an area where we thought there might be a Roman road, it's in close proximity to the Roman fort," he said.
"It is typical of Roman roads, it's one of those that link mid Wales, between the forts of Carmarthen and Llandeilo, through Brecon.
"It gives us the opportunity to look at the construction process in the Roman period.
"In places, you can see where the carts have pressed down on the stone."
Mr Fairburn said his team of around 20 archaeologists in the area were recording it.
He added that the pipeline would cut through part of the road but there were "significant parts we can preserve in situ".
"There won't be any significant damage. The county archaeologist has been out, he has looked at it, he's entirely happy with what's going to happen."
Community councillor Richard Field, from Cradoc, near Brecon, said the discovery, which is inside the Brecon Beacons National Park, had surprised local people.
The pipeline goes through the Brecon Beacons National Park
"It's incredible. It's only about 18ins below the surface," he said.
"This road runs alongside the camp and must link up from a road coming from the camp. It doesn't point directly at the camp.
"We used to play the village cricket match on this field. We'd sit on a slightly raised area to get a better view and didn't realise we were sitting on the causeway of a Roman road.
"I hope they take some care to look after this find and it's not obliterated but made available to subsequent generations."
The £840m scheme pipeline is part of a project that will see liquefied natural gas (LNG) shipped to Milford from the Far East and converted to natural gas at two terminals at the port before being piped to join the National Grid's main network.
When complete, the pipeline will run from Milford Haven to Gloucestershire and eventually supply up to 20% of the UK's gas needs.
A spokeswoman for National Grid said the company took its commitment to archaeology very seriously and had undertaken extensive surveys during the pipeline's planning process.