Ring of Bookan

In a talk at Orkney College the archaeologist Nick Card said that when he walked along the associated ridge it isn’t until you reach the Ring of Bookan that you finally see down into the Brodgar peninsula , and that it was being suggested that it was placed here as the demarcation between a settlement behind it and the sacred monuments below .
I now think his remarks actually refered to the Bookan chambered tomb further down .