Loie and I have had two Special Access Visits to Stonehenge. The first was several years ago, for sunrise, during Driving the Stone Age III. Last year, during DtSA VI (undertaken to attend the Megameet) we had a Sunset Special Access Visit.
It pretty much teemed rain our whole time on the site, and by about twenty minutes into our hour we were the only two visitors left. We had a nice chat with the guard.
Very atmospheric, being alone in Stonehenge in the English Rain and gathering darkness.