How to Install Maps as Wallpaper
Figure out the layout first and how you want to overlap the maps (original source unknown). If your maps have folding marks, iron them flat. To attach the maps to the wall, use wallpaper paste, ModPodge, or mix your own paste with one part white glue and two parts water. Now you can either apply the paste to the back of the maps or directly to the wall. I would coat the wall, it sounds much easier. Work in sections. If you go around windows, molding, etc., cut away the extra with a craft knife. Once the maps are placed, smooth the surface with a damp sponge. In addition, you could cover everything with a layer of watered down glue to protect the wall. I would only do this step if it was necessary for the overall look. Or use push pins for an easy no fail DIY maps wallpaper. See example here!
Your DIY maps wallpaper could be of faraway places and dream destinations, show were you vacationed, the area you live in, or simply choose maps with lots of ocean waters. If you love the look but not the multiple map layering idea, check out these Nautical Wallpapers. The selection includes nautical charts wallpaper and a large size charts decal from Pottery Barn.