Pretty medieval manuscript of the day isn’t a manuscript… it’s a box! Or rather, a chest designed to hold a manuscript. Made for the Treaty of Calais which was signed between Edward III and Jean II of France, it dates from 1360. The terms of the treaty meant Edward gave up his claim to the throne of France in exchange for the ancient territory of Aquitaine. You can find out more about the chest, and the treaty, on the National Archives website.
Image source: The National Archives (UK) via the Flickr Commons. No known copyright restrictions.