Update, there is a window in one of the dorm room towers at my Uni that is covered in layers and layers of dust. The stairwell up to that section of the tower is completely boarded up and impossible to get to due to the fact that four of the stairs are completely gone. Normally, as this room is completely cut off there is no lite in it or anything. So I was walking through campus the other night during a thunder storm, and suddenly a light flickered in the tower and there in the layers of dust read "Bad Wolf" a moment later when the lighting flashed the light went out, a flash again, and there appeared to be nothing but dust in the window. The next day I went past and there was no writing to be seen.