Leaders from the European Union's 25 member-states will gather at Áras an Uachtaráin this evening to celebrate the EU's biggest expansion, uniting the continent after half a century of Cold War division and creating a Union of more than 450 million people.
At midnight last night fireworks displays and flag-raising ceremonies - from the Mediterranean island of Malta to the arctic north of Finland, and from Poland's eastern borders to Ireland's western seaboard - welcomed 10 new EU countries.
The Commission President, Mr Romano Prodi, welcomed the EU's 75 million new citizens on "a historic day" for Europe.
"Five decades after our great project of European integration began, the divisions of the Cold War are gone, once and for all, and we now live in a united Europe," he said.
The accession of Cyprus, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia and Slovenia, which legally became EU members at 12.01 a.m, follows almost six years of negotiations. For the eight formerly communist countries joining today, the event marks the symbolic end of a 15-year journey back to the heart of Europe that started with the fall of the Berlin Wall in 1989.
Dublin will see its biggest security operation for 20 years today, with 5,000 gardaí and 2,500 members of the Defence Forces on standby. The organisers of a May Day protest said that security measures planned for Parkgate Street, near the Phoenix Park, were a recipe for confrontation.
The Dublin Grassroots Network has called on protesters to meet instead at the GPO at 6 p.m. today.
At a brief ceremony this evening the Taoiseach, Mr Ahern, will make a declaration on behalf of the EU and Seamus Heaney will read Beacons at Bealtaine, a poem he has written for the occasion. Children will present the flags of each member-state to the leaders before all flags are raised simultaneously.
After the ceremony the Taoiseach will host a dinner for the leaders at Farmleigh House, and most will leave Dublin later tonight. The British Prime Minister, Mr Tony Blair, will remain in Dublin for talks with Mr Ahern on the North tomorrow morning.
A weekend of celebrations began yesterday with symbolic events throughout the new member-states and on the borders between the old and new Europe.
In Prague the Czech Prime Minister, Mr Vladimir Spidla, said his country's membership of the EU marked "the end of a long and difficult journey".
The speaker of Slovakia's parliament, Mr Pavol Hrusovsky, said it was the fulfilment of a dream many thought impossible.
"For the generation that lived in the communist prison surrounded by barbed wire, the European Union is a dream come true. Fifteen years ago we would not even have dared dream this dream," he said.
