The Government is to apply to have the monastic settlement of Clonmacnoise designated as a World Heritage site.
The proposal is included in a new management plan by the Department of the Environment for the 500-acre site, which has ruins dating back nearly 1,500 years.
Its inclusion would make it one of only four sites in Ireland on the list, which is prepared by the UN's education and cultural agency, UNESCO.
On the list are the monastic ruins on Skellig Michael off Kerry's coast, the megalithic ruins in the Boyne Valley, and the Giant's Causeway.
The 754 cultural and natural sites of "outstanding universal value" on the list also include the Pyramids of Giza in Egypt, the Great Wall of China and the Grand Canyon in the US.
Launching the new management plan for the site, the Minister for the Environment, Mr Cullen, described the site as "unique".
The plan provides for protection and conservation measures for the site on the banks of the Shannon in Co Offaly. Much of the site is still in private ownership. However, 62 of the 67 major remains and artefacts are on land in State ownership. "In formulating this management plan, the objective is to make Clonmacnoise Ireland's third World Heritage site," the Minister said.
Originally founded in the 6th century by Saint Ciarán, the monastery ruins attract nearly 160,000 visitors each year. Artefacts and ruins include two high crosses, a round tower, a cathedral and a number of churches dating from the 8th century to the late medieval period.
According to a spokesman for the Department of the Environment, the protection plan will be financed through the €2 million which has already been allotted in the current National Development Plan for the protection and preservation of Clonmacnoise.
The plan is currently in draft form, he said, pending a public consultation. The Minister intends to make a formal application to UNESCO once this is completed by the middle of next year.
The application has to pass a number of hurdles, which could take up to two years before a final decision is made. The application is first referred to the World Heritage Bureau to ensure the technical aspects to the application are correct.
It is then referred to two non-governmental organisations, ICOMOS, the International Council on Monuments and Sites; and IUCN, the World Conservation Union. They will visit the site, compile a report for the bureau which then makes a recommendation as to whether it should be included on the list. The World Heritage Committee then makes a final decision.