This ancient castle of the county of Anjou is located on the edge of the D 55. You will not be able to miss it if you pass through Brissac during your outing.
Old Louet is a former branch of the Loire that is now half-filled. It was dug during the Middle Ages to develop fishing and fish farming. Some fishermen still catch salmon, shad, eel, pike or perch there.
I'm not a big fan of the Beaulieu forest, always ruts with water, paths that don't lead anywhere (the Komoot maps are not up to date), on the other hand …