This project started with our older girl wanting sleep in the same room as her younger sister once she was out of a crib. Since it meant no more sneaking into Mom & Dad's bed I was happy to comply. The only problem was all the plans I found were for one bed not two. Both girls love storytime in bed, so I had to make it strong enough for the whole family to be up in bed. To not turn her room into a construction zone, it was made in sections that could fit up the stairs & through the bedroom door.
All together we have a twin bed, a crib-size bed, three removable railings (to let me put them in bed when they fall asleep elsewhere), a slide anyone can use, a secret tunnel to crawl through underneath (and strong enough for adults to use as a step-ladder), a spiral stair for the kids to climb, and enough room for adults to sit up underneath. There is a flag pole next to the slide, but neither my wife nor I have gotten around to making them a flag yet.