Hi Dan & welcome
I've changed the thread title because I nearly didn't read it & thought others might avoid it too. You see, we've had several posters around here lately who have some very bizarre (to most of us) notions about megaliths etc & claim to have the answer to 'the riddles of the stones' and the like. (Often including invisible networks etc....)
Some of us have started avoiding posts that could be of this type... so, with the 'Stonehenge is in Ethiopia' heading, combined with your username (in particular if I'm honest)....
Anyway, I've come across (not first-hand, unfortunately) the stelae before - they're fascinating - and I for one look forward to seeing your shots of the burial chambers etc!
love
Moth