17.

The Phoenix crop circle is aligned on Silbury Hill. Here's a link to the map ( http://www.cropcircleconnector.com/2009/yatesbury2/comments.html ). That makes it on-topic. There's an unflattened heap of barley, at the centre of one of the circles, that resembles the hill itself. There's plenty of pictures of it on those pages. What's the meaning of that?