What happened here?

It tends to be a tad bit curious for the boys to quietly entertain themselves upstairs for any length of time. So when I hadn't heard any yelling, crying, etc. for half an hour one morning, I went to check on things. This is what I found.

Apparently, they decided to build a "fort". AJ's bed not only had the bedding stripped off entirely, but the mattress had been removed as well. Pillows and blankets from the guest bed had also made their way to the boys room to create the "walls" of the fort. I was pretty impressed with their efforts, I must say. Putting the rooms back together was another story.