Monterey International Pop Music Festival was a three-day concert event held June 16 to June 18, 1967 at the Monterey County Fairgrounds in Monterey, California. Crowd estimates for the festival have ranged from 25,000-90,000 people, who congregated in and around the festival grounds. The fairgrounds’ enclosed performance arena, where the music took place, had an approved festival capacity of 7,000, but it was estimated that 8,500 jammed into it for Saturday night’s show. Festival-goers who wanted to see the musical performances were required to have either an 'all-festival' ticket or a separate ticket for each of the five scheduled concert events they wanted to attend in the arena: Friday night, Saturday afternoon and night, and Sunday afternoon and night.
https://en.wikipedia.org/wiki/Monterey_Pop_Festival