GeoGraph - photograph every grid square

One of a pair of circles on this site. The nearby information boards give the following description of the northern circle:

Built before 3000BC as a timber structure and replaced by the southern circle, it lay hidden until the southern circle was excavated. The timber posts were replaced with stones, but the circle was never completed. A central stone lies on the north-south axis and the arrangement of postholes suggest it was built to mark the movement of the sun. The layer of stones spread across the centre of the site appears to be a deliberate decommissioning of the site.