I live in a 21 story apartment building in Chicago that I’d estimate was built in the 1950s, maybe early 1960s.
There is an east and west stairwell. Inside the stairwell are what look like a high school gym locker. They are numbered, one for each apartment.
What were these used for? Bread and/or milk delivery from the days of regular home delivery? Package/mail delivery?
They are certainly too small to be useful as extra storage.