The Crusades were important because they brought Europe into contact with cultures and ideas that were new and challenging in a culture that had been isolated and somewhat stagnant through the Dark Ages. As new ideas and materials came into Europe with the returning crusaders, interests in exploring and trying new ideas spread.
I would suggest the Reformation as an important event/process. The displacement of the Roman Catholic church as a primary power in governmental as well as religious concerns created new structures and relationships among social and economic classes and groups with far-reaching consequences. New patterns of thought and action followed and created demands for even more change.
Because of its profound impact on so many areas of human endeavor, which is the basis for all culture, I have to suggest the invention of the printing press as my third most influential force in the shaping of European culture. The spread of the printed word changed education, business, religion, exploration of the world - all important aspects of what we call "culture."