Post-apocalyptic Naruto
Here it is! The picture that shows Team Seven walking under a highway overpass. This picture is the basis for my belief that Naruto is set in a post-apocalyptic future earth. These people show no signs of using automobiles, yet there is a motorboat in the Zabuza arc. There is clearly electricity, and some technology. It's an odd mix really. Anyway, if there used to be a society with cars and airplanes and so forth, having old, no longer used highways like in this picture makes sense. So that's my theory. Feel free to call me a crackpot. ^^