One of the things that I remembered from my boyhood home in the 1200 block on 17th Avenue, was a license plate, nailed inside, at the bottom of the ventilation shaft for our home. One bathroom upstairs, and a toilet by the shaft in the basement.
It was a 1927 (?) license plate nailed to near the bottom of the ventilation shaft.
Was that kind of a "cornerstone" thing with the builders and developers?