In the 1960's in Japan, when the Maeda Outdoor Art Company unveiled a serpentine mound of polished concrete called "Play Sculpture: Stone Mountain," someone trying to be helpful told the artist, "If you'd just put a head on it, it'd be an octopus." It turned out octopus was what the park officials were buying, so octopus it was.
Though exact numbers are hard to come by, a Japanese fansite has documented over 100 remaining Tako-no-Yama [Octopus Mountain], which became beloved icons of Japanese childhood. They were each built by hand, sketched out onsite, first on paper, then in re-bar. Maeda claims that no two were alike.
Forget for a minute how cool and fun these things look. It took Richard Serra forty years to catch onto the fact that kids would love to scamper around a sinuous, curved fort space.
And forget the nostalgia that must kick in when a new generation of Japanese parents gets to watch their kids play on the Octopus Mountain range from their own childhood.
There's something just flat-out awesome about imagining a troupe of itinerant designers criss-crossing Japan, knitting the culture together with a common yet unique experience--concrete octopus slides!!--that sounds 100% completely wack. What a riot that must've been. America's Moon Bounce operators have a helluvalot of catching up to do.
[15 minutes later update: I just realized I tried to find one of these things two years ago in Tokyo; it was one of the first things posted on PingMag. Sure enough, there's my comment on 8/3/05, and here's the slide near Ebisu: #319. Glad we finally got that sorted out.]