When I was about 5 years old my sister and I had a cardboard Holly Hobbie house. We used to spend hours and hours in it. Eventually, one of the sides broke open. This was okay though, if not better, because when placed up against a wall or chair it doubled the space! I remember once my mom let my friend and I sleep in it all night with some sleeping bags; we felt so adventurous!
With my neck injury, it's kind of hard to go outside with both children by myself, especially in the winter. So needless to say, we're stuck inside the house most of the days. I always feel so bad for my kids and I imagine that they must be bored out of their minds. When I first had the kids I said I would never let their toys take over the house. But in all practicality, I ended up giving in. I try to make their time couped up with me less unbearable by making their surroundings more fun. I turn mattresses & cardboard into slides, tables & chairs into caves and swivel office chairs into merry go rounds.
I was reminded of my Holly Hobbie house when watching an episode of Max and Ruby (on Nick Jr.) who had a homemade cardboard castle. Last winter, I created a similar castle for my children and placed it in a corner of the dining room. To make it extra special, I made it "The Reading Castle". I placed all their books in it (using a diaper box as a shelf) and told them that books were only to be read in the castle. I taught them that books are special and should not be removed from their special place and thrown all over the house. This surprisingly worked! even though they're just 2 and 1 year old. The reading castle is their little hideaway for fun and has motivated them to go off by themselves to read more than before. I do however, have to occasionally squeeze my rear into the door to read with them. They love it! And so do I.