That's a dinky little application Oci, someone on Britarch was enquiring if such a thing existed recently.

Of course, in some cases it only has to be a bit wrong to be completely wrong, and it doesn't allow for tree cover. Or the height of the observer (I can see Silbury from a point near the Obelisk but my daughter cant!), but still, anything that will result in the rescue of Watkins from the clutches of the Mysterions is a good thing by me.