Floor turned Fort

We have these great interlocking blue mats in our "playroom" area, since we have hardwood floors on the main level. The other day I gave in and helped the kids turn the mats into a pretty nifty fort (usually I say, "That's the FLOOR! Leave it down!" when they try to play with it). They were very pleased with their fort and managed not to destroy it for maybe two hours. This is, in fact, noteworthy. These are two and four-year-old boys we're talking about! ;)