Firefly Planisphere Deluxe by Storm Dunlop and Wil Tirion at 15″ in diameter had print too small to read without magnification. Here is a 36″ version. The star chart is to sixth magnitude from the back of the original.
[CITATION] A Giant Planisphere in Color
Telescope, volume 23, page 203. Publication Date: 04/1962. Origin: S&T