I find myself noticing sign armatures more and more. Especially in this case, where the signs have long since been removed but the steel supports remain. These are especially apparent on the 1-story commercial buildings in my neighborhood. I think there are 3 generations of sign supports in the graphic above. Since roof signs are now prohibited by the zoning code (with some exceptions) these things no longer serve any purpose whatsoever. Still, easier to leave them. At least until they rust away and crash to the sidewalk.