If there was a period I could return to, it would be the era of the civil rights movement, especially in US soul from the era. There was a recent film made, or at least produced, by Questlove about a concert in Queens, and that I would love to have attended. The music of Curtis Mayfield, Donny Hathaway, Stevie Wonder, and Marvin Gaye in that period is unsurpassed, IMO, let alone the music of artists like James Brown, Nina Simone, and Sly and the Family Stone, who all played important historical and musical roles.
I know, such a long concert was not expected. Heck, they could have done two and noone would have complained. Massive respect to them for that. The only other artist I saw that matched the 4 hours was Stevie Wonder at the NEC. Another superb performance.
I was told Springsteen used to do four and a half in his younger days, the Trojan. He did 3 hours when we saw him for the first time this year and he never took a break. At the age of 72! What a trooper.