In the kitchen photos of my last post, you might have seen this gem.
Yes, that's the chimney to the house.
Yes, that's a hole.
No, we did not put it there.
Yes, we will fill it.
So what is it? Well, when we took down the cabinets, there was a pie plate - the metal kind - nailed to the wall here. I peeled it off before the sheetrock came down (seeing as this is not an exterior wall, so it wasn't covering an old exhaust)...and found a hole. With soot. Our best guess (and our plumber agreed): the vent to an original wood stove (house is circa 1929).