European Union leaders have attended a gala concert in Berlin celebrating the 50th anniversary of the bloc, which was founded by the 1957 Treaty of Rome.
EU leaders have been attending a series of celebratory events
The concert was followed by dinner for the 27 leaders at German President Horst Koehler's residence.
A leader's summit on Sunday will endorse a statement emphasising the EU's achievements and challenges ahead.
In the city, there will be street parties and fireworks with UK singer Joe Cocker giving a free concert.
Chancellor Angela Merkel will use Sunday's summit to relaunch the debate on the EU's stalled constitution, rejected by French and Dutch voters in 2005.
But correspondents say the statement will mask divisions among EU members.
"We, the citizens of Europe, have united for the better," says the draft statement, known as the "Berlin Declaration".
The statement, drawn up by the EU's German presidency, hails some of the EU's achievements over the past 50 years, including open borders, the common market and the euro, and an end to Europe's Cold War divisions.
The unnatural division of Europe is now consigned to the past
We, the citizens of the European Union, have united for the better
We preserve in the European Union the identities and diverse traditions of its member states
We are united in our aim of placing the EU on a renewed common basis before the European Parliament elections in 2009
The BBC's Oana Lungescu in Berlin says there is no explicit mention of the most divisive issues - future enlargement to admit Turkey and the Balkan nations, and the EU constitution.
Just weeks before the French presidential elections, and faced with stiff opposition from the Czech Republic, Poland and Britain, Angela Merkel has chosen the vaguest of terms, our correspondent says.
A single coded reference to the constitution talks about "placing the EU on a renewed common basis" before the 2009 elections to the European Parliament.
Dutch Prime Minister Jan Peter Balkenende said it was best to avoid the word "constitution".
"It's a very good declaration and what we need now is a change of treaties," he said.
Germany hopes that a new text can be agreed by the end of the year, or early next year at the latest, so that it can be ratified by mid-2009.
Many European leaders believe the project will come unstuck again if member states decide to ratify the treaty by referendum.
This two-euro coin has been minted to mark the 50th anniversary
But a poll by a British Eurosceptic think tank, Open Europe, suggests that three-quarters of Europeans would like a referendum on any new treaty giving more power to the EU.
According to the poll, carried out in all 27 EU countries, 41% of people in the EU would Yes in such a referendum and the same proportion, 41%, would vote against.
However, a majority would vote No in 16 EU countries, including Germany.
British officials say that if the new treaty is very small, and contains only a few of the ideas in the original draft constitution, there will be no need for a referendum.
Ms Merkel told reporters that the city of Berlin itself was testimony to the importance of European unity.
"A city that was once divided and is now re-united... stands symbolically for what has succeeded in Europe over the 50 years," she said.