The Ring of Brodgar is the 3rd largest neolithic henge in the UK. It's exact build date is unknown, though it is likely to be between 2500BC - 2000BC.
I took this at sunset on my first evening on the islands. I was touring Scotland, loosely following the NC500 but I decided to take a 3 day detour to the Orkney Islands. 😠It is a place I look forward to visiting again soon along with Shetland.