In depth: What Schengen zone expansion practically means - je 21.12.2007

Europeans have been enjoying border-free travel among most western and central european countries for years, thanks to the Schengen treaty, named after the town in Luxembourg where it was signed. The orginal agreement included only a handful of western EU countries. Now the Schengen zone has expanded to a total of 24 states. Here's a closer look now at the treaty and what it means for Europe