Today marks the 40th anniversary of Altamont, the infamous free concert thrown at the the Altamont Speedway, east of Livermore near the junction between 580 and I-5. The concert was billed as Woodstock West, and headliners The Rolling Stones had imagined a utopian gathering, initially planned for Golden Gate Park, in which the admission charges and confusion of Woodstock could be avoided. In the end, one of the largest gatherings in California history ended with the deaths of four people, and the Rolling Stones ringing in the end of the 1960s with the song "Street Fighting Man." This dark day was recorded in the Maysles brothers' documentary Gimme Shelter (trailer after the jump).

San Francisco city officials had initially agreed to the GG Park idea, but insisted that the permit was contingent on the concert not being announced until 24 hours before. Mick Jagger either didn't know or didn't care about this contingency, announced it anyway, and the permit for the show was revoked. The concert plan then moved to Sears Point, now Infineon Raceway in Sonoma, where a stage was being constructed 10+ feet above the audience. Had the concert happened there, says Grateful Dead publicist Dennis McNally, "nothing would have happened."