For a long while I've wondered exactly where Haradon Hill is, Stukeley makes many references to it in his description of the alignment of the Avenue...
In order to have a just notion of this avenue, it is necessary to go to the neighbouring height of Haradon hill, on the other side the river. The largest barrow there, which I call Hara's and which probably gave name to the hill, is in the line of the avenue; the ford of Radfin lying between, as we see in the last Plate. I stood upon this hill May 11. 1724. during the total eclipse of the sun, of which I gave an account in my Itinerarium. Here is a most noble view of the work and country about Stonehenge. Whoever is upon the spot cannot fail of a great pleasure in it; especially if the sun be low, either after rising or before setting. For by that means the barrows, the only ornaments of these plains, become very visible, the ground beyond them being illuminated by the suns slaunting rays. You see as far as Clay-hill beyond Warminster 20 miles off. You see the spot of ground on the hill, whereon stands Vespasian's TAB. XXVI. camp, where I conjecture the avenue to Stonehenge began, and where there was a sacellum, as we conceive. From hence to that spot a valley leads very commodiously to Radfin, where the original ford was.
... especially where it crosses King Barrows Ridge, looking eastwards.
When you are gone a little farther toward Stonehenge, and arriv’d at the top of TAB. XXIV. the hill, if you turn back you have the view presented to you like that TAB. XXIV. beyond A the beginning of the avenue, is Radfin, beyond that XXVIII. Haradon.
It's labelled on Andrews' and Dury's 1773 Wiltshire Map - revised 1810 (why is there no entire image of this map online? The extracts are always too small) but not on more modern maps, so pinning it down is tricky. I want to go and look at "Hara's" barrow.
From Andrews' and Dury's Wiltshire Map (1810 revision)
Stukeley's engraving of "The back Prospect of the beginning of the Avenue to Stonehenge" showed me a familiar horizon - I recognised the shapes of those hills...
The back Prospect of the beginning of the Avenue to Stonehenge (Stukeley, 6th Aug 1723)
... and not having a photo to hand, I turned to Google Earth, whose landscape elevations have got a lot better over the last few years.
Google Earth overlaid with Stukeley's image for comparison
Nice one William, now that I know what barrow you're talking about I can go and stand there just as you did.
Whoever is upon the spot cannot fail of a great pleasure in it; especially if the sun be low, either after rising or before setting
(For slightly larger versions of the images, view the attachments directly)