The infamous 'Rock & Roll Circus' featuring Jethro Tull with a pre-Sabbath Tony Iommi on lead guitar...
Love this very much I didn't start my life sentence until 1975, if I could time travel to see any live music from before my time then the Isle of Wight Festival of 1970 would make my top ten Having just looked I was totally unaware that the Isle of Wight Festival 1968/1970 is widely acknowledged as the largest musical event of its time, greater than the attendance of Woodstock! https://en.wikipedia.org/wiki/Isle_of_Wight_Festival_1970#Performances