I'd never come across it before either and I think it is is quite a groovy thing, despite getting it wrong (for me) on so many counts. I find this image from that website epic, righteous and strangely moving.
As Maryhill was believed to be a a more accurate model of what Stonehenge may have looked like , it was chosen in preference to the actual site to provide data for the acoustic measurements of the proposed soundfield of the original site .