In Richard Bradley's book of the same name, he put forward the following theory regarding Silbury. Now those of us who have walked the area round Silbury one of the things that becomes apparent is its visibility within the landscape - it can be seen as far away as Compton Bassett.... you can play the "Silbury Game" walking down past the Overton Barrows and see its top just above Waden Hill.... it is part of a 'circular landscape' of the late Neolithic. Windmill Hill, an earlier monument, also followed this circular pattern with its three ditches with their different offerings...
He puts forward the theory that the Sanctuary, which originally had a timber circle, (replaced at a later date by the two circles of stones depicted in Aubrey's drawing,) that this original timber circle was roughly the same size as the first stage, (the primary mound) of Silbury; in other words, similar to Stonehenge, there was a moving of particular aspects of the landscape from one place to another, maybe the turves that were used in the interior of the primary mound would reflect this. The platform on top of Silbury was almost the same size as the floor area of the primary mound, which it would have centred on vertically below.
Also, Silbury Hill is similar to the size of the late Neolithic palisaded enclosure on the valley floor nearby, I presume he means by this the final stage of Silbury, the palisaded enclosure also had a timber circle within it.
Monumental architecture, such as WKLB and Silbury function within the wider aspects of the landscape as symbolic reminders of that which is 'past' they carry in their memory, old ritual structures, which they have replaced, in this instance the old 'memories' of the Sanctuary would be carried forward to Silbury...
Which is clearly at odds with Burl , who says that Silbury was a territorial marker...;)