Cambridge is an amazing city ... even if you are just visiting ... my list of tips will be different, having studied there, but from a travel perspective.... do go punting on the river Cam, visit the Colleges for the feel and architecture (especially Kings, Trinity and Johns), visit nearby Grantchester village and laze in the Orchard there (the haunt of Ludwig Wittgenstein, Virginia Woolf, John Maynard Keynes, Rupert Brooke and others of the Bloomsbury Group), laze around in Jesus Green, have a pint at the nearby Rat and Parrot pub, visit Heffers and the loads of other bookshops there, stroll around the Market Square, eat at a riverside restaurant or cafe, watch a play in the one of the college gardens, and attend a lecture or so if you can... easily reached from London in less than an hour by train ...