The Grateful Dead wrought a psychedelic revolution upon the cultural landscape of the Sixties. They also kept the spirit of the Sixties alive in the decades that followed, building a massive, supportive network of fans known as "Deadheads." The Dead and their peers on the San Francisco scene helped steer the adventurous rock audience of the mid-Sixties toward a brave new world of sound in which albums supplanted singles and concerts became improvisational marathons.