Stonehenge 181
Image by wysefool

yeah I read that but it seems odd they made such a big mistake.
There are holes on the tops of the others but these are only small.
PeteG

yeah I read that but it seems odd they made such a big mistake.
Ahh... which brings us neatly back to the possibility of a roof - can't quite see it myself but don't think it should be dismissed out of hand.

PeteG,
Perhaps the holes are smaller because, learning from their previous mistakes, they checked the holes regularly, and realised their mistakes sooner.
Just a thought,
TE.