Most people, as children, dreamed about discovering new worlds or whole new worlds in the home they live in. For a child, their home, and a few other places, are all they know. It is no wonder that they seek to see new magical and wonderful things in that world. You are doing the same thing by watching these videos, even! From classic bookcase entrances to the future of cellars, here are 15 genius hidden rooms and space-saving ideas.