It was one particular slice of the history that was more or less re-created this night, with King and Taylor building a set around songs they did in a star-making stint for which they shared the stage in 1970, when he was the rising-star headliner and she a hugely successful songwriter but not a performer up to that point, serving dual roles as band member and opening act.
But there were some who weren't aware of all that -- though they were largely among the handful too young to have experienced it as it happened.
There was, for example, the 28-year-old Troubadour bartender who said she knew little about the club when she found the job posting on Craigslist not long ago.
And there was the 18-year-old kid brought by his father -- none other than Eagles bassist Timothy B. Schmit.
"I know William Shatner is here," Timothy B. Schmit Jr., said of the night's significance, pointing to one celebrity in attendance.
Surely he knows that his father's band coalesced in this very room.
"No," he admitted. "I didn't know that."