When scouting out Tohoku on Google Maps, I noticed this weird-looking area in Akita prefecture:
Here it is closer up;
I remember seeing this circular-river looking area on sufficiently large maps of Japan while I was living there, too. It looks so... weird and unnatural. What the heck is it?
Well, I looked into it a bit, and the name of the area is 大潟村, Oogata-mura (mura = village). I found their website, which explains that it is the result of an enormous land reclamation project. Apparently, it was originally the Hachirogata lagoon, the second-largest lake in Japan. Then, over the span of 20 years and at a cost of 85.2 billion dollars, finishing in 1977, they lowered the lagoon water level with pumping stations to convert the lagoon bed into an enormous stretch of flat, fertile farmland, and then built a planned community on it. I guess they decided to do this because flat farmland is so hard to come by in such a mountainous and densely populated country.
I am both very impressed and slightly disturbed. Dude. It's just so... science-fictiony, don't you think?