Archaeologists have unearthed the extensive foundations of medieval Carrickmines Castle, which served for years as a garrison fort to defend Dublin against marauding raids by the O'Byrnes and O'Tooles of Wicklow.
The excavation, which has been under way since last August, is one of the largest to be carried out in Ireland since Wood Quay and involves upwards of 80 archaeologists from 12 countries, some from as far away as Australia and New Zealand.
It is being directed by Dr Mark Clinton, a veteran of the Wood Quay dig in the late 1970s, on behalf of consultant archaeologists Valerie J. Keeley Ltd, under contract to Dún Laoghaire-Rathdown County Council, at an estimated cost of €3.5 million.
The site, straddling Glenamuck Road, lies directly in the path of the South Eastern Motorway and will be obliterated by its Carrickmines interchange. It adjoins land owned by Jackson Way Properties, which is being investigated by the Flood Tribunal.
Speaking to The Irish Times yesterday, Dr Clinton said that if the remains of Carrickmines Castle lay on a greenfield site unaffected by motorway plans, he had no doubt they would be preserved as a national monument because of their significance.
Built by the Anglo-Norman Walshes in the 13th century, the castle saw a lot of action over the years because of its crucial location in protecting the Pale against attack by the Wicklow tribes. Its military use continued until 1642, when it was destroyed during a siege.
That happened after the Walshes changed sides to join the Great Rebellion of 1641, leading a revolt by south Co Dublin against its English overlords.
The Walsh stronghold was eventually sacked by a force led by Sir Simon Harcourt, who died in the effort.
Earlier, in 1599, when the Walshes were still loyal to the crown, a troop of cavalry known as the Earl of Southampton's Horse was billeted at Carrickmines Castle. But this force was routed that summer by the O'Byrnes, who burned all before them.
"The most gruesome finds we've discovered so far consist of disarticulated limbs," said Dr Clinton. "We also found a crude burial pit containing the remains of 18 females from the late Elizabethan period. One of them had an axe wound to the back of the head."
Many of these women, who were apparently aged between 18 and 20 when they died, had silver coins stitched into their clothing - unknown to their killers. He said these coins are in "excellent condition" and would ultimately end up on display in the National Museum.
Up to 8,000 shards of medieval pottery and more than 10,000 pieces from the post-medieval period, when the castle was replaced by a manor house after 1642, have also been discovered; these are being held in plastic bags in one of the site huts to be catalogued later.
The finds also include prehistoric flint scrapers and cut-marked rocks, mainly from the neolithic period, which provide evidence that the area was inhabited at a very early stage. Further such finds are anticipated as the layer of topsoil is peeled back by tracked diggers.
But the most important aspect of the excavation has been to reveal the extent of the castle's enclosure and parts of its fosse (or moat). Though only the rubble granite foundations remain, Dr Clinton can still point to where a drawbridge was located during more troubled times.
The stone walls, which were razed to ground level after 1642, were probably topped by a timber palisade. And though no evidence of the Pale ditch has yet been found on the site, he said that was still a possibility as it is "heading in this direction" from the west.
The general location of Carrickmines Castle was already known to archaeologists, even though all trace of it had vanished under farmland.
What they did not know until the excavation revealed it was the full extent of this important military outpost of the Pale.
The current exercise is described as "conservation by record". As Dr Clinton said, "all we can hope for is the opportunity to record and retrieve". It will be up to Dúchas, the Heritage Service, to decide what happens to the stone enclosure now being uncovered.
"It has to be fully revealed before the road goes through," said Mr Noel Madden, general manager of Velerie J. Keeley Ltd. But with 14.5 kilometres of motorway to build, there should be no rush to evacuate archaeologists before their painstaking work is finished.