Fifty years ago, during a few short weeks in the summer of 1967, thousands of hippies descended on San Francisco. The small suburb of Haight-Ashbury became a centre for sexual freedom, freedom to experiment with mind blowing drugs, to debate social and economic utopias and freedom to listen to loud rock music. Marco Werman looks back at those hedonistic times through the music and recollections of people who were there 50 years ago.