French Revolution
Retreat of the Mongols in the 13th century
Fall of the Roman Empire
Reformation

And so on... you can't really say there's a 'most important event', because unlike America history (no offense intended here), there are a whole lot of different point of views there. As a French, I'd say the French Revolution/Napoleonic Era, but people from Italy and Greece might say 'the beginning/end of the roman empire', people from Eastern europe might say 'the retreat of the mongol hords' or 'the Yalta treaty',etc.