Border checks at nine Eastern European countries vanished on Sunday allowing free trade and movement for hundreds of millions of Europeans.
The Schengen agreement is a system that helps make the dream of European unity a reality and it seen as the last phase in dismantling the Cold War's Iron Curtain dividing eastern and western Europe.
But what is the negative side of Schengen? And how would European politicians address the main concerns that accompany an increasingly border-free Europe?
Inside Story, with presenter Imran Garda, investigates.
Watch part two of this episode of Inside Story on YouTubeThis episode of Inside Story aired on Monday, March 31, 2008 at 17:30 GMT
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