Campaigners opposed to the route of the M3 motorway near the Hill of Tara carried the flags of all 32 counties in a protest march in Dublin on Saturday.
They gathered at the Garden of Remembrance and marched to the Department of the Environment at the Custom House. The marchers included the artists Louis le Brocquy and Anne Madden.
While the event organisers Tarawatch said that more than 1,000 people had participated in the march, other estimates put the number at less than 500.
A petition calling on Taoiseach Bertie Ahern and Minister for the Environment John Gormley to re-route the M3 is to be delivered to the department today.
A spokesman for the Minister yesterday repeated that Mr Gormley did not have the power to re-route the motorway and to suggest otherwise was misleading.
The spokesman added that Mr Gormley had appointed a leading expert on the archaeology of Tara, Conor Newman, to a committee to advise on the excavation of the national monument on the route at Lismullen. Recommendations were being followed "to the letter", the spokesman said.