You hinted at it, but do we have any idea why this location was selected for the building of Stonehenge?Since Facebook's message system limits the message length, I am replying here.
If memory serves, it so happens that there is a subtle astronomical relationship between the 'standstills' (extreme rising/setting points of the sun and moon) at Stonehenge's latitude. There are 4 particular spots around Stonehenge where there are or have been markers of some kind, such as standing stones. One could use these markers to observe the standstills. The curious thing is that these spots form a rectangle. If Stonehenge had been built a few miles north or south of the spot it is on, i.e., at a different latitude, these markers would not have formed a rectangle but a non-rectangular parallelogram. Thus it appears that the original builders chose that particular latitude in order to take advantage of that fact. The amazing thing is that archaeological evidence indicates that the very first structure at Stonehenge was erected around 8000 B.C., which is basically at the end of the last ice age. So the shaman types who were running the show back then apparently already had enough astronomical smarts to figure that out.
Another factor in the choice of location is that on the Salisbury plains where Stonehenge sits has a relatively clear view of the horizon all the way around. Other places have too many trees, hills, etc. Even so, the ground is not exactly level at the site. Nonetheless, the final architect who designed the actual henge (hanging stone) structure, managed to do so in a way that the upper surface of the megalith ring is within about 6 inches of being level across its whole diameter. This is also amazing given that the builders had only the crudest of stone tools to shape the stones.
There are lots of amazing things about Stonehenge. I'm sure there are more we have not learned yet, and some we may never learn.