I live in a house built around 1905 and I noticed when knocking on one of my living room walls, that that has no windows on it, a certain area makes a rattling sound like a window pane or a something similar. Other parts of the wall don’t make that sound at all, and now I’m very curious if there’s an original window under there!

Anyone have any ideas on the best way to peak in there without damaging whatever is in the wall, and without cutting out a huge section?
I have one of those tiny camera tools to see in right spaces so my original thought was to drill a hole and use that tool?