I am on the second floor of an old house in the northeast USA. There is another one at the entrance to the second floor, this at the backdoor. The button looks like a bell but what is the hole for?
Here are some of the answers:
1. One of them said: Honestly you might be able to speak into it and hear whoever is at your door when they speak back
2. One of them also said: How old is your house? Looks like a C. 1920s light switch. Are there modern light switches underneath both? The light could have come out of the hole long ago (screwed in there, maybe a lantern-style electrical light)
3. Other response was: Perhaps just another eyehole or peephole. Like a handicapped accessible hole.
