I was lucky enough to hear David Field's lecture The Stonehenge Landscape Project at Devizes last month.
He mentioned the possibility of there having been a central mound in Stonehenge that predated the stones. I know he has yet to release his work but I am not trying to steal any thunder here as others have previously publicised this.
It is important to note that this mound might be an artefact of the various excavations of the twentieth century but this 1875 photo, and
others, show the ground rising quite clearly before then. So I think we can say it is an original feature.
The mound shows up clearly on a contour map of Stonehenge. I have circled it and the North and South Barrows in Red.
Stonehenge contours at 0.075m intervals - © A. Johnson 2008
Source - sarsen56: "A surface contour map of Stonehenge. The ground rises from c. 100m above sea level on the east, to c.103m to the west...note the mounded area within the centre which appears to predate the stones"
There doesn't seem to be any records of any excavations where the mound is which would tell us if it is natural or not. Walking round Stonehenge it looks unnatural.
We also don't know if the Barrows, which aren't Barrows of course, predate the ditch or not. We know they contained central stones, did the middle mound also have one? Is there a stonehole waiting to be found?
Put these unknowns together and there is a hypothesis that the original feature of Stonehenge was a line of three man-made mounds with upright stones. It is only a wild hypothesis, but it is one that can be tested.
PS
Wiltshire Heritage Museum: Additional Stonehenge lecture: Disappointed to miss David Field's lecture The Stonehenge Landscape Project: recent analytical survey and investigation in the World Heritage Site? Good news - he will be giving the lecture again on 10 March 2012. Book
on-line now to reserve your ticket ...