The destruction of the Tara-Skryne valley was "cultural vandalism akin to ripping a knife through a Rembrandt", the Dáil was told during a bitter debate about the M3 motorway.
Labour TD Mr Emmet Stagg (Kildare North) said it was a fact that the road "will destroy the most valuable archaeological, literary and historical site in the country, revered all over the world".
Quoting Irish emigrants who expressed their "horror and disbelief" on an electronic petition organised by the Save the Tara- Skryne Valley Group, one asked: "Are you really going to send millions of tyres over the graves of the high kings?"
He described the Hill of Tara as "as much a symbol of our national identity as the Tricolour.
"It dates back 6,000 years and during most of that period it has been used as the major sacred site in the country."
Mr Stagg called on the Taoiseach to "declare himself as a man of cultural understanding who has the courage to be the 'Taoiseach' in the real sense of the word - the leader or chief who defends Tara from its latest invaders". But the Minister for communications, Mr Dempsey, a TD for Meath, questioned the Labour Party's motives and said they would delay the motorway indefinitely. The road was necessary and would go ahead.
He claimed the Labour Party was trying to get the Government to do what Labour wanted, or they or their associates would drag them through every court in the land. He was speaking on the second night of the debate about the M3 motorway through the Tara-Skryne Valley.
The Labour Party, in a Private Members' motion, called for the Government to discontinue the plans for the M3 route.
Labour leader Mr Pat Rabbitte hit out at Mr Dempsey and said his own party wanted the road built without the costs of litigation.
Mr Arthur Morgan (SF, Louth) said that motorists from Cavan would be tolled three times from Cavan to Navan, Navan to Dublin and then the "modern highwaymen" would toll them again at the M50.
The Opposition rejected the Government amendment which, while "bland and meaningless", was voting down any possibility of a Dublin-Navan rail rink, and any immediate decision to move on the bypasses around Dunshaughlin, Kells and Navan.
Local TD Ms Mary Wallace (FF, Meath) said, however, that Opposition proposals made no sense because they would move the road closer to the Hill of Tara. She said it would make no sense to the people she represented, who were hard-pressed commuters.
Minister of State for Heritage, Mr Ivor Callely, said he was fully aware of the history and heritage of Tara. He insisted that a route be carefully chosen to avoid the "core zone" around Tara.
Mr Eamon Ryan (Green, Dublin South) warned that no matter how wide they built the motorway, it would lead to traffic lights on approach to the M50, and "they're going to queue there and block up there for the same four hours that they're waiting at the moment. On pure transport terms this is madness and needs to be stopped." The motion was defeated by 66 votes to 58.
