Littlestone,
>You can say that again; but it seems to me that constructing Stonehenge, so close to Avebury, was a statement of some sort; what that statement might have been is a whole new can of worms.* <
Maybe there was a reaction to Avebury, years later someone said "Let's beat that." Let's face it, competition in modern times leads to building envy, not that it usually results in a similar improvement.
Cheers,
TE.