Besancon castle has museums and a zoo inside the fortress, the latter using the defensive walls as the parameter of the tiger and babboon enclosures. I went this morning and stayed until mid afternoon. The castle itself has a history of being captured and then reinforced.
Tonight had a gig in the hostel itself, the ground floor doubles as a nightclub (not just people stqying in the hostel). Think the French version of a barn dance.
I'm going down with a cold. :(