The Hill of Tara is one of Ireland's - and many say Europe's - greatest archaeological treasures.
By James Helm
BBC Dublin correspondent
The hill has been regarded as Ireland's 'spiritual centre'
For 4,000 years this low, grassy hill to the north-west of Dublin was a ceremonial capital.
It was a spiritual and political centre, the seat of Ireland's High Kings.
Today, it is a tourist attraction for thousands of day-trippers, who can wander around the gentle contours and gaze across the surrounding countryside.
But the Hill of Tara has retained its mystical place in Ireland's heritage and consciousness.
Plans to build a four-lane motorway nearby have caused outrage amongst many environmentalists, academics, and others, who have said it would be an act of historical vandalism.
The letters page of the Irish Times newspaper has conveyed the anger and concern of objectors around the world.
Muireann ni Bhrolchain, who lectures in medieval Irish studies, described the plan to build the motorway a mile from the Hill of Tara as "like deciding you will preserve St Peter's Cathedral but drive a motorway through the square".
The long-running argument over the siting of the road has reflected some of the tensions created by Ireland's "economic miracle".
Dublin has out-grown itself, and is now home to about one third of Ireland's population of four million people.
As car ownership has increased in recent years, so Ireland's creaking infrastructure has come under severe pressure.
As the country's wealth has grown rapidly during the past decade or so, so too have the commuter towns around Dublin.
Their residents face a daily struggle down poor, congested roads to work.
In County Meath, where the Hill of Tara sits, the journey of 30 miles or so from the growing town of Navan into Dublin can take up to two hours at peak times, along the single-carriageway stretch of road.
Many of the area's residents are people who have left the capital to escape soaring house prices.
Now, faced with the difficulties of commuting, many of them support the road building plan.
As one resident put it: "We have a right to a modern road in the year 2005. I spend more time in my car than with my children."
So after lengthy consultations and much bitter debate, the Irish Government has paved the way for the proposed M3 motorway to go ahead.
It says it is putting checks and balances in place to safeguard the area.
A total of 38 archaeological digs will be carried out along the route before any construction work begins.
One group, which has campaigned against the road plan, told the Irish Times the decision was "undoubtedly the worst planning decision in the history of the state".
Ciaran Cuffe, a Green Party member of parliament, said: "A motorway and a spaghetti junction this close to one of the most historic and sacred sites in Ireland is an enormous mistake.
"This is a bad day for history, for heritage, and for the Hill of Tara."
Across Ireland, road projects are being carried out, aimed at upgrading the country's transport links.
The whole Tara affair has demonstrated the difficulties involved in trying to match up economic needs with cultural and historic sensitivities.
Many residents stuck in traffic jams in County Meath may welcome the news.
But with legal challenges to the decision to go-ahead with the project looking very likely, it may be a few years before the bulldozers and construction teams move in near to the grassy undulations of the Hill of Tara.