The real question there is, was it meant to appear octagonal or was it built that way to make construction easier (after all anyone who's ever layed any bricks/blocks will know it's easier to lay them in a straight line using a string than it is to lay a curve), and then rounded off with fill when it was complete.....like the "cased" pyramids.

We're not even sure if it was built in steps or as a spiral, though the spiral theory makes a heck of a lot more sense for lots of reasons.

This is one of the main reasons for my becoming interested in whether or not there were "Silburies" in the first place......they really need to be identified and investigated.....it's difficult to study a unique object and come to any meaningful conclusions about its use/form/construction, as any of these factors may have been simply down to the whim/idiosyncracies of the builders.

By identifying them and understanding them, we have a far better shot at understanding the big Sil herself.