In World War II, pilots and their crew took cloth maps on missions over enemy territory to be able to find their way back in case they wound up behind enemy lines. Cloth maps don't tear or make noise and can be hidden more easily than paper maps.
One such map was used by a B-17 tail gunner named Tom Osborne. He marked all the missions on the map by circling the towns and dating them. This website seeks to tell the story behind the map.