There are two tourist trails in Mont St Michel: one is the Abbey, the other a collection of houses and museums that work together. Amongst these is the House of Bertrand du Guesclin.
The house is a museum, largely dedicated to his wife, who was famous locally as a sorceress and astrologer. Whereas the knight was often away on military business, his wife was kept safe in this home, looking at the stars and casting her horoscopes.
The museum is small, presenting the house on its three flours and small garden. It is atmospheric and though some of the furniture postdates the happy couple, it is a nice attraction where you will be able to spend a half an hour or so away from the crowds in the main street.
For non-French visitors, this small museum could be seen as a waste of time; those with some knowledge of who this woman was and the times she lived in (when most such women were hunted down by the Church and often executed) will find it interesting that she was kept safe only a few yards from one of the world's most famous abbeys!
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.