A recently discovered photo from the National Archive shows a Fallout Shelter sign being hung at the former Christopher Columbus High School in the North End (now residences) on December 3, 1962.
The photo description says this sign was being hung on the North Bennett Street side of the school, and it has since been removed. However, one sign remains facing Tileston Street
The first photo appears to go into a boiler room or storage area, while the second is in the cafeteria and lists a capacity of 200. All the interior signs are believed to be gone.
These signs were posted almost a month after the first sign was posted in Massachusetts at the State House.
© 2019 Fallout Five Zero
Exterior photo retrieved from Archive.org on December 3, 2019
First Interior photo retrieved from Archive.org on November 20, 2019
Second interior photo retrieved from Archive.org on December 3, 2019
Modern photos of former Columbus High School taken in November 2019 and property of Fallout Five Zero
Fallout Five Zero 
We had an interior sign in our elementary school lunchroom and two exterior ones on the school pillars. I used to be terrified of them, now I collect them. Go figure. 🙂