A small structure with a climbing wall, hanging swing, and a little house like interior, children could play house, have an adventure or even just see who could hang the longest if they felt like it:Toys and Playgrounds
When I was a kid I had a fascination with building forts. I used whatever was at hand... blankets and pillows, cardboard and chairs, in fact anything that could provide 'cover'. In my head, this is what they looked like. Were you there with me?