The three Baltic states halted land and sea border controls at midnight (2200 GMT) meaning their citizens can travel all the way from northern Norway to Portugal, thousands of kilometres (miles) away, without showing a passport.
Six other countries -- the Czech Republic, Hungary, Malta, Poland, Slovakia and Slovenia -- were to join an hour later.
The Rosella, a ferry from existing Schengen member Finland and the first vessel to dock as the frontier fell, was serenaded by a border guard orchestra as it arrived in the Estonian capital Tallinn.
"The free movement of people is one of the main rights of human beings," European Commission president Jose Manuel Barrosso said in the Estonian capital Tallinn.
"The expansion of the Schengen treaty on Friday makes it the best day of my life," he added.
The addition of the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia and Slovenia to the Schengen Treaty zone saw ceremonies take place along the old perimeter between East and West, 18 years after the fall of the Berlin Wall.
Austrian Chancellor Alfred Gusenbauer and Slovak Prime Minister Robert Fico symbolically sawed through a frontier barrier at the Berg/Petrzalka crossing point between their countries to start three days of commemorations for the landmark change.
"We are standing here at the border between Bratislava and Vienna to take away the most important symbolic barrier," said Fico. "From midnight tonight, you can travel 4,000 kilometres (2,500 miles) from Tallinn in Estonia to Lisbon in Portugal without any border controls."
"When people go to Bratislava in 20 to 30 years, they will ask where the border was here at all," Gusenbauer said.
At St. Margareten in Austria and Fertorakos in Hungary, the two countries' interior ministers, Albert Takacs and Guenther Platter, dismantled the barriers at the crossing point, where, in 1989, their predecessors had cut the fence that symbolized the Iron Curtain.
Czech and Slovak interior ministers marked the elimination of police checks at Europe's youngest frontier, formed when their two countries were formed from the 1993 split of former Czechoslovakia.
"I do not know if this frontier was useless or not, but we can rejoice at its disappearance," Slovakia's Robert Kalinak said before fireworks and a folk concert at the border between Stary Hrozenkov and Drietoma.
The frontier change has not been without opposition in the existing members however.
With 1,260 kilometres (780 miles) of borders with Schengen newcomers, Austrians have expressed concern that lifting controls will bring a crime influx.
An ORF public television poll put the number of Austrians opposed to the lifting of barriers at 75 percent.
In Warsaw, the head of the EU's border watchdog, Frontex, Ilkka Laitinen, warned that illegal immigration would be the price Europe paid for Schengen expansion.
But political leaders were eager to play down such fears.
Schengen "is not about criminality, it is not about insecurity or fear. It is a bigger zone of peace, security and stability," Austria's Gusenbauer said.
Finnish Prime Minister Matti Vanhanen was to travel across the Gulf of Finland to Tallinn, Estonia on a ferry, minus the usual travel formalities.
Malta, the EU's smallest state prepared to dismantle checks on Schengen zone citizens disembarking on ferry boats and cruisers with a government delegation due to test their new freedom on a boat trip to Sicily on Friday.
The 15 older signatories to the 1985 treaty were: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain and Sweden.
Britain and Ireland have not joined Schengen and new EU members Bulgaria and Romania are not yet allowed in.
Güncelleme Tarihi: 21 Aralık 2007, 14:22