The Thumb Octagon Barn, located near Gagetown, Michigan, is nearly 100 years old. It has an exciting history and is the largest Octagon Barn in Michigan. James Purdy, a local banker, contracted the Munro Brothers to build a barn, later known as the “Air Castle”. It was built from tall timber on the 560 acre farm, which was near Mud Lake, also on the property. Mud Lake was lined with peat bogs which could be a power source to run an electric power generator, all planned out by Mr. Purdy. The farmhouse was as unique as the Octagon Barn. They built a brick, 15 room farmhouse where they raised their two daughters. Mrs. Purdy kept a daily diary of life on the farm and especially the “Air Castle”. Her diaries made it possible to create the video history of the Thumb Octagon Barn. The video is 43 minutes in length.