The history of Cambridge is intertwined with the history (and birthplace) of America, and it's a daunting thing to cover in a mere entry. However, your one-size-fits-all, best bet for a quick immersion would be to start at America's first university, Harvard University.  Harvard was founded in 1636 as a training school for Puritan clergy, and from that auspicious debut it has gone onto creating a lot of history.  In fact, General Washington and his American Revolution cronies hid in Harvard for awhile during the war!  Taking a tour of Harvard will teach you a lot about the land's history and what goes on there, and you could also take a peek at Harvard's spectacular museum collections.  The Widener Library, for example, is a good place to go to on a tour because then you can see an original Gutenberg Bible.  Besides Harvard, though, the best way to get a sense of Cambridge's history is to take a walking tour of some sort.  Plaques and signs litter the area, saying "John Adams was here" and all sorts of fun facts.  Look up Cambridge's home page to see if they offer any sort of history tours, and do make sure to go to the famous Mt. Auburn Cemetery, a historically important cemetery which houses tons of famous dead people, from Isabella Stewart Gardner to Longfellow, who changed Cambridge and the world for the better.