September 27, 2013 - October 06, 2013 - CONFIRMED!
From Oktoberfest Denver Website:
September 27-29th & October 4-6th
Fred and Hertha Thomas owned two shops in Larimer Square (Cafe Promenade and Boutique Int'l). In 1969, they decided to honor their favorite tradition in front of the Cafe, and quietly tapped a keg and served some pretzels and white radishes. Until 2007, the event was held on the 14th block of Larimer St. and since it has been hosted at 20th and Larimer in historic Denver, Colorado. The Denver Oktoberfest attracts over 350,000 people during the six-day festival and it was quoted in Maxim Magazine and USA Today as "The Best Oktoberfest" in the United States and "One of the country's biggest and longest running traditions".