found this on a 1960 house today
Did you open it?
If is is on the second floor perhaps a laundry chute
or a old clean out for a chimney
Looks to be in front of the toilet - good spot to hide the Playboys.
It could be this - http://www.flickr.com/photos/retrorenovation/3524697387/
How convenient, you can weigh yourself before and after you “take the kids to the pool”!
Just an FYI, you left the Address as the name of the photo.
lolol now that was a good one