August 15, 1969. On 600 acres of field owned by a dairy farmer, 400,000 young people kicked off this seminal event of the 1960s. The three-day music festival had a roster of many of the era's top musicians. Richie Havens, Jimi Hendrix, Joe Cocker, the Grateful Dead, Janis Joplin, Crosby Stills and Nash, and The Who were just some of the performers.