Have you ever looked at a toy or adventure that a kid has and thought, “Man, where was that when I was their age?” If so, then these play structures designed by the Danish firm Monstrum Architecture will more than likely cause some serious envy.

Founded by Ole B. Nielsen and Christian Jensen, Monstrum aims to reflect the imaginations of children in their designs. We have to say it looks as though they’ve succeeded with designs that include wobbly and lopsided castles, whales, serpents, and ships sinking into the sand.

These storybook-esque structures offer something to marvel at with their brilliant design, and of course, all that childish envy.

If you’d like to see more of their designs check out Monstrum’s site.