Events around EuropeWhile Dublin will be at the centre of EU celebrations on Saturday, with all 25 leaders taking part in a ceremony at Áras an Uachtaráin, there will be dozens, if not hundreds, of parties, ceremonies and fireworks displays throughout the rest of the Union as well - especially in the accession states.
All the EU institutions in Brussels are opening their doors to the public for the day, and the streets around the European quarter will host festivals reflecting European diversity. Farmers from all 25 countries will advertise their produce in a park opposite the Commission headquarters, which will also be occupied - quite appropriately - by 25 hot-air balloons.
There will be 70 concerts throughout Europe to welcome enlargement, the biggest of which - in Berlin and Warsaw tomorrow evening - will be broadcast live around the continent. Many of the new member-states are planning New Year's Eve-style events tomorrow night, with Prague's National Theatre hosting a gala concert followed by a fireworks display at midnight.
Cyclists will converge on the Slovenian capital, Ljubljana, from three border crossing points tomorrow, and bonfires will be lit throughout the country. At midnight, church bells will ring, fireworks will explode and fire alarms will sound while 25 ships light up the river near the city centre.
Austria is staging a series of symbolic events on its borders with Hungary, the Czech Republic, Slovakia and Slovenia. The presidents and foreign ministers of Austria and Slovenia will meet at a border crossing point tomorrow.
Estonia will mark its entry into the EU by encouraging citizens to plant trees all around the country, while the president of Latvia will address the public in Riga's Dom Square on Saturday. Fireworks, flags and the playing of the European anthem will celebrate EU membership for Lithuania at midnight tomorrow.
Hungary will stage dozens of events, including an open-air concert in Sopron, where East German refugees crossed into Hungary on their way to the West in the summer of 1989, precipitating the opening of the Berlin Wall a few months later.
Malta will be celebrating for the whole weekend, with concerts, pyrotechnical displays and a giant video projection on Fort St Angelo.
Paris begins a 10-day Festival of Enlargement tomorrow, celebrating the culture of the EU's new member-states in concerts, exhibitions and conferences. In Rome, the celebrations will be high-minded, with conferences on the European constitution and gatherings of earnest young Europeans.
The Netherlands will mark the occasion by constructing a Eurovillage on an island in the Hague and with an EU quiz with "small EU gadgets" as prizes.