This is the inside of Callahan's Nose Tunnel on the former L&N Cumberland Valley Division. It was last used in 1986, and has now been abandoned (and was so when this shot was taken). Known to train crews as "Dark Tunnel," the bore was in service in 1890. L&N's largest and best steam locomotives, the M-1 class "Big Emmas," regularly blasted upgrade through here (you're looking up a 1.25 percent grade). About 1950, a southbound coal train plowed into the standing caboose of a local freight that was just behind the photographer. The mid section was brick-lined for stability, since this runs through a fault line in Stone Mountain.