I'm the new owner of a 1956 Southern California home and discovered this curious plate on the stucco exterior:
[![plate screwed into the stucco][2]][2]

It's above, and to the left of the front door. There is a working sconce mounted above the same door.

[![location photo][1]][1]

Removing it revealed that there are wires inside, which makes me think that it's a junction box (just a guess - I'm not sure of its purpose). Regardless, I think it should have a weatherproof cover (the hole in this one is concerning) that can easily be removed & replaced in the event that electricians ever need access (this one was siliconed around the edges to seal it)

[![behind the plate][3]][3]

The box is round has 2 screw holes, presumably for attaching a cover, that are approximately 2-3/4" spacing. I searched for round junction box covers and they all seem to be 4" diameter these days. What's the proper way to cover this?

[![measurement of distance between screw holes][4]][4]


  [1]: https://i.sstatic.net/oybsp.jpg
  [2]: https://i.sstatic.net/gorsr.jpg
  [3]: https://i.sstatic.net/GAJ6x.jpg
  [4]: https://i.sstatic.net/ynrKv.jpg