OK, cool.
Let me explain in a little more detail what the site looks like. It's been ten years. I drove there in 1999 so I'm not entirely trusting my memory, but I think the idea of it being exposed from the surrounding forest may still be valid. We were traveling southeast.
We drove down a two-lane highway, A344. I remember a slight rise in the road as I saw Stonehenge on the right. My wife was looking to the left and didn't see it so I had to keep pointing it out to her. We had only been in England a couple of days and were still disoriented by needing to concentrate on driving on the left, figuring out roundabouts, and manuevering a car with the steering on the right. (Think, "I have an outrigger to my left" and you'll be fine.)
Stonehnge did not appear overly large, but it was an easy stone's throw from the highway. The parking lot was to the left. We paid our pounds and walked through the museum, getting one of those translator bars to listen to the narration. We walked through the tunnel with the forest mural and came out in open air. It wasn't until we wandered about the site that I saw another highway intersecting the one we had driven in on below stonehenge (A303). I'm trying not to exaggerate here, but I would guess that other highway was 100 feet below Stonehenge. The land sloped away toward the highway gradually, but you definitely had to look down to see the other highway. The traffic noise was clearly audible. It was a busier highway than the one we had driven up.
The land itself can be described as rural. There were a lot of grassy fields nearby and farmers' fields of wheat (They would say 'corn') further on. To the left across the parking lot in the distance there was a ridge of land running parallel to 'our' highway. You could see structures on it. After visiting Stonehenge we went up the ridge to view the burial tombs of ancient kings. One of the farners had a home-built crop circle in his field. He did it with his tractor. We were told the burial tombs were intentionally situated with a view over Stonehenge much like people wanted to be buried near St. Peter on Vatican Hill.
If you have Google Earth, just type in 'Stonehenge, England' and you'll be taken right to it. You can see the A344 highway in yellow. The A303 is in green. Stonehenge is toward the top of the triangle you see. If you zoom in you can see the parking lot and visitors center and even the tunnel that goes below the highway. Google Earth suggests there is only a 50 foot drop to the highway intersection, so too bad we don't have a topographic map. I can buy one for $50, but hey! This is just a forum topic.
In any case, Stonehenge is definitely higher than the surrounding land. I've lived in the midst of forests all my life. They do not always 'carpet' every square mile. Very often there are fields in the midst of the forest--especially where there are differences in topography and therefore differences in climate. A hill exposed to wind, for example. I maintain that a forest of deciduous trees (as opposed to much larger conifers) would be an environment where Stonehenge could be used as a 'clock' or 'computer'--especially if the residents cleared away a certain portion of trees around this small hill.
The idea of stoned-out British hippes from 4000BC grooving on a concert at Stonehenge is kind of amusing. I assume they painted theor bodies blue.