Oktoberfest is the most famous and some may say infamous festival of Munich. It is held annually and lasts two weeks. The first Oktoberfest was held in 1810 to celebrate the marriage of Prince Ludwig of Bavaria and Princess Therese. This festival begins at the end of September and ends in early October. With six million attendees, it is most certainly the world's largest fair. Beer plays the key role in this festival. 

More Festivals in Munich
Corpus Christi
Cycle Race
Fasching Festival
Maidult Fair