Ah, yes. The playhouse. That place where our first nesting desires, those urges to love were we live, were born. I had two: one in that storage area under the stairs in the basement, and an outdoor crow's nest with swings and the requisite "Members Only" sign. There were, of course, no members, but that's the sorta thing a clubhouse should have, is it not?
And some more contemporary options:
See more of Alix's groovy collection at Modern Kiddo