Ken Kesey’s psychedelic “Furthur” bus has returned to San Francisco after decades and is now the centrepiece of a new Grateful Dead exhibition. The bus was used by Kesey and his Merry Band of Pranksters during their 1964 cross-country journey, which helped spread the emerging psychedelic counterculture. The exhibition also features Jerry Garcia’s BMW and will launch an effort to restore the now-dilapidated bus.