If the ancients believed that the sun, moon and stars went into the earth when they set then Silbury's flat top would have been a landing spot for the moon. The december moonset (16th ?) is just past the full moon (14.4 days) and should be the best chance for testing this theory - weather permitting, of course.

In the South Tyne valley there is the equivalent of Sil. Hill, though it is natural. Many stones and cairns point toward it, yet climbing it and being on the summit feels 'all wrong'. On the other hand, Rivington Pike, a similar hill but in Lancs., still has an annual spring fair - presumably an ancient leftover, when eggs are ceremoniously rolled down the slope.