Hit the library and search for "maze" and "labyrinth." You might come up with some surprisingly good stuff that way, just by accident. That's how the history stuff came up. I found a book about it--too high a reading level for him, so I read it and translated the material to him--and we talked about it. The history of church mazes as a meditative tool is pretty interesting, and could lead to some interesting geography lessons if you look at where the mazes were/are located. We didn't go this far because his interest was waning by this point. But it was possible.
