The Ness of Brodgar Excavation continues to uncover fascinating information about Neolithic Orkney:

At its zenith, in the main phase that we are currently exploring (dating from c 3100BC), the Ness was dominated by huge freestanding buildings flanked by a pair massive stone walls.

The best book on the Ness at present is The Ness of Brodgar: As It Stands (Orcadian, 2020)

I am very keen to visit this and other sites in Orkney at some point!