Blymyer Building, Cincinnati
This 1912 photo of downtown Cincinnati is very cool in general (such bustling energy!), but even cooler is this inset photo of the top of the Blymyer Buidling and this glorious ad:
Unfortunately, it's not a fading ad now, since the building no longer exists - still, this is the most extensive "building directory" ad I've ever seen. That building apparently was quite the mecca of the writing trade - two typewriter dealers, a printer and a stationer.