What really means the word "borders" in European inter war period ? Barriers, meta-frontiers, insuperable divisions between pieces of Europe. Borders divided not only Nation-States, authoritative regimes and democratic ones, but above all were becoming the pretext for aggressions, for the building of a New Europe : the Nazi's Lebensraum. Borders were becoming front lines. After the Second World War new borders will be laid out in a more pacific spirit. However Europe has to waif until 1989 to find again her real borders. Classification JEL: N00, F00.