This is the kind of scene that can and should induce heart palpitations in parents.
That said, they had a good time, and no one was injured.
This is at Robinson Park in the town of Sandstone, MN, on the banks of the Kettle River. There is a wondrous pile of sandstone slabs, striking terror into the hearts of many a parent, but nevertheless available for climbing. My kids, well, if there's danger, they'll go for it.
This used to be a real quarry, for the sandstone that lines the banks of the river and that gives the town its name. After the mid-20th century, apparently it became much more cost-effective to build out of cement block, never mind that sandstone buildings last forever and have a timeless quality about them. But the quarrying couldn't have gone on forever either. And so it goes.
Anyway, this park is a wonderful, out of the way place to have lunch and take a walk.