I didn't know these things existed. That is until last year when we helped a friend move and I inquired about a little door to a compartment that had another little door to the outside.
She said it was a milk door, where the milk man delivered the goods. Like a secret passageway? Or the little conversation slot in a confessional? I was so intrigued. I wanted to take a saw to that section of the house and cut the whole thing out to study further.
I didn't of course, but it would be cool to have one in our house! Especially now that the milk man has returned! What a fantastic idea.
Image from Flickr/aptrail2005