I spent today at Himeji. It was the castle of the first shogun, with a history going back to the 14th century. The current castle was first built in the 17th century, making its history as old as that of Matsumoto, though as I can tell, the latter gets the nod in original construction.
The printed guides unfortunately provided only lackluster historical details, so I did not get a real sense of events surrounding the castle. I did enjoy some more of that wonderful Japanese woodwork. In the 50-60s, they replaced the central support pillar, and the old one is on display. Impressive pieces of wood, especially considering it has been dead for four centuries.
I noticed a repeated pattern of triangle-square-circle. I asked around, but could not find its meaning. I got a sense it was not original with the castle.