What is this?

So, on the light by the front door of the place I'm staying there's a most unusual structure. You can see it dangling from the bottom right corner, shaped somewhat like a tiny hot-air balloon with the opening at the bottom.

It's clearly a nest of some kind, but what kind of creature made it? It's too small for a bat or even the smallest bird.

My first thought was that it might be a dirt-dobber, though an unusual one. But cautiously touching it reveals its not made of clay dobbing, as I thought, but grey paper, which makes me think it's some kind of solitary wasp. At any rate it's not doing anyone any harm.

Thanks to Janice K. for the photo.

--John R.