Going back to what you said earlier, about the place where you always feel like you're being followed, I have a similar experience almost every day, although it isn't (as far as I'm aware) related to any ancient sites.

I walk down a small country lane to get to the station every morning. There is one part of the walk where the path becomes a sort of green tunnel due to overhanging trees, and whenever I get about 30 yards down this, I have an overwhelming urge to turn round, as though I'm certain there is someone looking at me from behind. There never is. Spooks me out every time. As this happens regularly, there must be something that triggers it, but I'm blowed if I know what.