Wiki page: Sasha Stone, he and his wife, Cami Stone, who was a photographer as well, were association with Dadaists and Walter Benjamin.
I went to Germany with my family a few years ago, they are like the world leaders in interesting playground equipment. There were all kinds of cool things that could injure you - zip lines, climbing walls, trampolines, etc - and there were always kids outside playing on them.
Well there are plenty other places that have interesting equipment, too, but compared to many US playgrounds and the culture hostile attitude for risky equipment I see what you mean. This playground item with a fall height of 1.6m and 6m total height (so as high as as a 2 story building with a ceiling level might interest you: https://www.hst-spielgeraete.de/spielplatzgeraete/klettergerueste/kletterpyramiden/raumnetzpyramide-spider-6-kletterpyramide::148.html
There is a lot to be said about playgrounds and kids play. There are some more natural or reform pedagogic ideas, there are socialist ideas, there are more kid centered ideas in which they create stuff (there is a playground the kids themselves with real tools create the play items). I do think that especially within cities kids need spaces that are safe and yet injure prone enough that kids can try their abilities.
Here are examples of play grounds within Tiergarten from contemporary times:
https://image.jimcdn.com/app/cms/image/transf/dimension=664x10000:format=jpg/path/s6b475586b582e4aa/image/i434511c7d6005f97/version/1583740798/image.jpg
https://www.spielplatztreff.de/blog/auf-spielplatz-tour-im-berliner-tiergarten/
