Celebrations have been held after midnight to mark nine new states joining a European border-free zone.
The Schengen agreement, which allows passport-free travel across the area, now embraces 24 nations.
Some 2,000 people celebrated with the EU anthem, Beethoven’s Ode to Joy, and fireworks in the town of Frankfurt on Oder at Germany’s border with Poland.
The Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, Slovenia joined the zone.
German Chancellor Angela Merkel and Polish PM Donald Tusk will mark the event on Friday morning in the town of Zittau, near the point where Germany, Poland and the Czech Republic meet.
Crime wave fears
They will be joined by Czech PM Mirek Topolanek and European Commission President Jose Manuel Barroso.
On Thursday a checkpoint between Austria and Slovakia was dismantled in one of several events marking the enlargement from the Baltic Sea to the Adriatic.
Slovak Prime Minister Robert Fico and Austrian Chancellor Alfred Gusenbauer sawed through a barrier at the Berg border crossing.
Other ceremonies took place in Hungary, Slovenia, the Czech Republic, Poland and the Baltic states.
These Polish officials held their own celebrations as the EU extended the area for passport-free travel to include eight former communist countries in Eastern Europe, plus Malta.
Initially the lifting of internal controls involves just land and sea borders, but that will be extended to airports at the end of March 2008.
Mr Gusenbauer welcomed the extension of the Schengen zone, rejecting fears that it might create a crime wave in Austria.
The European Commission says that one billion euros (£720m) has been spent on beefing up security on the new EU frontiers, including the establishing of missions along the Polish and Slovak borders.
Mr Fico said: “From midnight tonight you can travel 4,000km (2,485 miles) from Tallinn in Estonia to Lisbon in Portugal without any border controls.”
Although the enlargement allows passport-free travel throughout the area, travellers can be asked to carry documents by any of the countries concerned.
These Estonian border guards were on duty as passport checks were being eliminated at land and sea ports. Airports will follow at the end of March 2008.
For non-EU nationals, a Schengen visa allows travel across all the participating countries.
Thirteen existing EU states have already been part of the Schengen accord as well as two non-EU countries, Norway and Iceland.
The UK and Ireland are not involved in the zone – which embraces 400m people – but they have signed up to agreements on security.
A significant element of the Schengen agreement is the Schengen Information Service (SIS) which features an enormous database in the French city of Strasbourg.
The SIS database enables police in any Schengen state to find out whether a suspect has been involved in any kind of crime across the EU.