Leaders from the EU's 10 new member states have been marking their countries' entry into the European Union with speeches and televised addresses.
Street parties have been held across the new EU
Here is a selection of what they and other European leaders have been saying.
European Commission President Romano Prodi:
Welcome to the new 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 live in a united Europe.
Irish Prime Minister Bertie Ahern, President of the European Council:
To the people of Europe who are joining us today in the European Union I
extend the hand of friendship. It was your democratic choice and your own efforts that made this day
happen. Today marks the triumph of your determination and perseverance over the
legacy of history. For Europe, today marks the closure of one chapter and the opening of
another new and exciting chapter in its long history.
Former Polish president and Solidarity trade union leader Lech Walesa:
I fought for our country to recover everything it lost under communism and the Soviets... and now my struggle is over. My ship has come to port.
Polish President Aleksander Kwasniewski:
We have passed the test of being Europeans.
Slovenian President Janez Drnovsek:
Dreams from 1991 are becoming reality. We will build good relations between nations and people. We will strive towards mutual respect and equality of every individual, sex, race and national or any other minority.
Lithuanian President Arturas Paulauskas:
History will rectify its greatest mistake tonight: Lithuania, the geographical centre of Europe, is returning to Europe. Today, we are saying to the old continent: Hello Europe, we are coming. We are coming to live together, to work together, to create together, yet to remain ourselves.
Hungarian Prime Minister Peter Medgyessy:
We used to be the gate to Europe and will
continue to be so, but there is a crucial difference; we are
now inside the gate.
Slovak President Rudolf Schuster:
We should take care to see all our citizens boarding the (EU) train - not to turn it into a privilege for only the richest. This is one of the reasons why the responsible politicians in our country should choose for our train into the future a speed which will take into account that not all of us are equally strong and fast. Let us, therefore, wish each other a happy journey towards our better and more beautiful future.
Czech President Vaclav Klaus:
As from midnight today the Czech Republic will no longer exist as an independent state entity and it will become a part of the EU... Today we are gaining something, but also at the same time losing something.
Estonian Prime Minister Juhan Parts:
We are returning to where we belong, to a community that
shares the same values and visions.
Cyprus President Tassos Papadopoulos:
We don't want to celebrate the joys and fortunes of EU accession on our own, we want to share it with the Turkish Cypriots. As legal citizens of the Cyprus Republic they have every right to this joy and prosperity. We wait for them. Their place is with us.
Latvian President Vaira Vike-Freiberga:
We have passed all the tests, we have met all the requirements, we have achieved what many, including ourselves, did not believe we would be
able to attain.
Malta's Archbishop Joseph Mercieca:
Malta in Europe should not consider only material benefits, it
should also take into account its Christian roots of our country and
Europe. Through its words and deeds it should assist so that the
community of people in the EU understand and feel the need of God
French Prime Minister Jean-Pierre Raffarin:
I have tears in my eyes about this subject. I am part of a
generation that believes in Europe. Europe is the force
that prevents hate from being eternal. We must open our
hearts to this new Europe.
German Chancellor Gerhard Schroeder:
Enlargement will not make us poorer, but richer in the future.
Former German Chancellor Helmut Kohl:
We never want to wage war again against each other. We want to
honour the dead and tend to the graves but we never again want to
have soldiers' tombs in Europe. That is the most important reason
for a united Europe.
Swedish Foreign Minister Laila
There was a time when Europe's countries negotiated with each
other by sending tanks. The enlargement we see today is fantastic.
The Cold War's division of Europe into east and west is melting away
once and for all.