I wrote about missed opportunities of the San Francisco Main Library and the architect I. M. Pei in May 2011. Since I'm always passing by the Main Library, I was there to pick up a couple of books on the 4th floor and went up the stairs. I hadn't noticed these handrail brackets with the little rectangular box attachment to the wall before.
This was an interesting detail as it looks to be specifically designed for this building with its high round atrium "lobby". Beyond its simple geometric shape, I'm trying to discern how it fits into the overall design concept of the library. Not everything needs to have "meaning" but I was just wondering . . .