Environmental campaigners and residents' groups will hold a gathering at the ancient Hill of Tara in Co Meath this weekend in protest at plans to build a €680 million bypass through the area.
An Bord Pleanála recently gave the go ahead for the N3 by-pass between Clonee and Kells in a move that has angered heritage campaigners and local people.
Mr Vincent Salafia, an American-trained lawyer and a spokesman for the Carrickminders group campaigning against the construction of the final leg of the M50 motorway across the site of Carrickmines Castle in south Dublin, is among those co-ordinating the event.
He told ireland.comhe believed the decision needed to be challenged. "I feel it [An Bord Pleanála] is now becoming a rubber stamp for the Government and that it is not fulfilling its duties under the National Monuments Act."
Mr Salafia said there was no "set agenda" for the weekend gathering, but that it was being held with a view to focusing protest and to establishing some sort of umbrella body representing those opposed to the road.
Mr Salafia added the threat to the Hill of Tara site now needed to become "a national issue" rather than just a local issue.
He said the National Roads Authority argued that the new road would be further away from the ancient site than the existing N3. However, the construction would destroy a number of sites of historical interest, which would be merely logged and then "bulldozed over".
Those campaigning against the construction of the by-pass under the current plan say the curtilage of sites such as Tara should also be protected under the National Monuments Act, and they are seeking legal advice on this issue.
Mr Salafia claims the motorway will destroy at least 141 sites associated with Tara. He also says the validity of the Environmental Impact Statement (EIS) conducted for the motorway project should be challenged on the grounds that it does not propertly address the impact on the archaeology of the area.
Mr Salafia said meetings would take place at the Hill of Tara from around 8 p.m. on both Friday and Saturday nights.
A number of bodies, including motoring organisations and some Meath residents, are in favour of the by-pass. The NRA and Meath County Council claims it will significantly reduce traffic congestion in the burgeoning towns of Dunshaughlin and Navan and will cut the travel time to Cavan by as much as 30 minutes.
Those campaigning against the motorway as it stands include the Columban Missionaries based at Dalgan Park just south of Navan on the N3. The Columbans will lose land at their Mission Awareness centre, which is also the site of a wildlife reserve and is widely used as a leisure park by the public.