The UNI4 bus route runs between Addenbrookes Hospital & Madingley Road, linking many University sites. The bus stops outside Darwin College on Silver Street, and those with a valid University Card benefit from subsidised fares (a single fare currently costs 90p). For a timetable and full route details see http://www.admin.cam.ac.uk/offices/em/travel/bus/uni4.shtml [1]
Links:
[1] http://www.admin.cam.ac.uk/offices/em/travel/bus/uni4.shtml