The Oktoberfest tradition started in 1810 to celebrate the October 12th marriage of Bavarian Crown Prince Ludwig to the Saxon-Hildburghausen Princess Therese. The citizens of Munich were invited to join in the festivities which were held over five days on the fields in front of the city gates. The main event of the original Oktoberfest was a horse race.
Oktoberfest is the world's largest funfair held annually in Munich, Bavaria, Germany. It is a 16-day folk festival running from late September to the first weekend in October with more than 6 million people from around the world attending the event every year. Locally, it is often simply called Wiesn, after the colloquial name of the fairgrounds themselves. Other cities across the world also hold Oktoberfest celebrations, modeled after the original Munich event.