The Bayeux Tapestry tells the story of the last successful invasion of England in 1066 by William, Duke of Normandy... William the Conqueror.  It is actually an embroidery, not a tapestry, done on a 70 meter-by-half-meter strip of linen.  It is in a remarkable state of preservation due largely to the fact that for its first seven hundred years it probably never saw daylight, and saw light of any kind only on special occasions.
When you first enter the Museum of the Tapestry, you may choose to go straight to the tapestry or to go through a pre-exhibit consisting of replica-sections of the tapestry with explanatory text.  Invest the time to do the pre-exhibit.
We spent 2 hours getting prepared and watching a short movie about the origin of the tapestry.  We highly recommend this method because you only get to spend about 15 minutes viewing the real thing.  Being prepared makes the experience much more understandable and enjoyable.
See http://www.aemma.org/onlineResources/bayeux/bayeuxIntro.html for a brief history and http://panograph.free.fr/BayeuxTapestry.html for detailed views of the tapestry itself.  I have pictures too, but they're from low-light situations and these are much better.
While you're enjoying the tapestry, note how much the Norman ships resemble Viking longboats.  "Normans" were originally "Norsemen".  That section of France we call Normandy was long ago invaded, conquered, and settled by Vikings.