This probably wouldn’t pass any safety test. It comes from the age when hanging by your knees upside down on monkey bars without an adult in sight was the norm.
As a child I used to love to go to the school playground across the street from my grandparents’ home. There were seesaws, a merry-go-round, monkey bars and swings. I had to cross a busy road to get there. I don’t have any recollection of an adult ever supervising the crossing or the play. Our playmates and siblings solved their issues with each other and learned in the process how to deal with the world at large. We went home (across that busy street) when we scraped a knee…often coming right back to spin, swing and climb again.
This might not be the safest choice, but it sure looks like it created a ton of fun and could again. By the way…I’m not a proponent of hanging by your knees.
It’s at Tom Gibbs Studio in Fall River, Massachusetts.