I've always liked Silbury Hill and the surrounding countryside/megalithic sites. My personal theory about why it was originaly built is quite simple. Seeing as its quite close to Avebury henge, could it have started life as a place to put the earth and chalk that was excavated during the henge building ? Avebury henge is rather large and makes Stonehenge look like something you would build in a sandpit. If you go to it now a lot of the ditch has filled up and im sure it would have been twice as deep.
However I'm not sure on the strata of the mound, but if it is in layers like earth, chalk, earth and so on it would sort of support my theory (i think). Then years later it may have been used for more ritualistic purposes as it is at the end of the avenue and seperates the avenue from West Kennet Long Barrow.
Reading the article it mentions medieval post holes and a military connection, watch tower maybe ?. what's everyones thoughts ?
Thinking about Sibury Hill reminds me of something that happened to Ian, Danny, Craig and myself there many years ago. We had stopped off on the way home from the 2nd Great Glasonbury Adventure to have a look, and decided it would be a good idea to have a bite before continuing on. So there i am setting up the camp stove and some bloke wanders over an asks if we are performing a ritual, i said yes, we are going to break bread before this mighty structure and pulled a can of beans out of my bag. He wasnt too impressed