I finally got a decent shot in that hallway.
As a school, the panes contained "Privacy Glass", something quite
common in older bathrooms. The surface was not flat, it usually
contained a pattern which let light thru, but there was no way anyone
was going to see anything thru the glass. Add to the fact
that the room in back of the glass was always dark, few people knew
what was there.
If it weren't for the doors, these mirrors would hide all traces
of that room behind them