One of the best kids books I have listened to so far.
Great for kids imagination and also education about times and places throughout history and the world!
I love the story 9-16, but I couldn't buy books 1-8 because it started with two kids went to a stanger's tree house uninvited. In books 9-16, when the kids go for an advanture, they didn't inform their parents where they were going. It might be confusing for little kids, and it concerns me to get more of this series for my kids. Other than that, it's a great book, well written.