Assuming the top of Silbury was designed to be flat it follows that it was designed to be flat for a reason (well, that's not for sure of course but it's a reasonable assumption :-)
Question. I've always thought a Stonehenge-type structure on top of Silbury would look rather nice and I seem to remember that the size of area at the top of the Hill is very close to the area that Stonehenge occupies (I know the top of Silbury has been messed about with a lot but the respective areas do seem to be pretty close). Now... if a bit of bluestone has also have been found up there as well that's rather interesting; it doesn't prove anything of course but... I just wonder... mmm... did Stonehenge once sit on the top of Silbury Hill?
Ducks, heads for cover and awaits the fallout (and if I don't come out until Tuesday it's because I'm in Avebury until then... yippee!).