On July 5, 1968, Bill Graham opened the Fillmore West with the Paul Butterfield Blues Band, Ten Years After, and a third act advertised as "Truth," in the former Carousel Ballroom at the corner of Market and South Van Ness. It was the birth of the room that would define the San Francisco concert experience for the next three years -- Graham's flagship, the West Coast counterpart to his Fillmore East in New York.

The move had a story behind it. Through early 1968 the Carousel had been run by a musicians' collective -- the Grateful Dead, Jefferson Airplane, Quicksilver, Big Brother, operating as Headstone Productions -- trying to build a venue bands controlled. It failed. Bad bookings, a lease the critic Ralph Gleason called "the stupidest in show business," mounting debt. When the collective fell far behind on rent, Graham took over the lease. He was also ready to leave the original Fillmore Auditorium: the surrounding neighborhood's decline, the hall's modest size, and the collapse in attendance after the assassinations of Martin Luther King in April and Robert Kennedy in June had all made the old room untenable. Fillmore West would run until July 1971.

The opening bill was a pure blues-rock statement. Paul Butterfield was a top-tier act four albums deep, Chicago-blues credentials intact even after Mike Bloomfield's 1967 departure. Ten Years After, with Alvin Lee, were a promising young British band on their first American tour -- their star-making Woodstock performance still more than a year away. As for "Truth": the advertised third act, but the performance and recording evidence shows Fleetwood Mac actually played that weekend. The substitution itself was never documented -- one of those small mysteries the record leaves unresolved.