On this day in music history: December 6, 1969 – The Rolling Stones headline a free concert at the Altamont Speedway in Livermore, CA. Originally intended to be held at Golden Gate Park in San Francisco, the concert is moved to the Altamont Speedway at the last minute, fifty miles away when an agreement cannot be reached with SF city officials. Attended by over 300,000 people, the concert alsos feature the Jefferson Airplane, Santana, The Flying Burrito Brothers and the Grateful Dead. As they had done with their Hyde Park concert earlier in the year, The Stones hire Hells Angels to do security for the event. Unlike that event which is peaceful and goes off without incident, Altamont turns violent and ultimately tragic when concert goer Meredith Hunter is stabbed and beaten to death by several Hells Angels when he brandishes a gun and waves it at the stage. The incident is captured on film, featured in filmmakers Albert and David Maysles’ documentary “Gimme Shelter”, released the following year. The incident signals the beginning of the end of the counterculture movement in the US, which peaked with the Woodstock festival just a few months before.