The road on Percy Rigg runs from Rosedale Head to Guisborough. The section that runs over Percy Rigg is called Ernaldsti, after Ernald de Percy, Lord of Kildale. On a grim drizzly day I decided to walk the road from its junction with the Kildale – Commondale road to Percy Cross.
The surrounding moors are also dotted with standing stones, some are prehistoric, others are estate boundary stones. 
There are the remains of a large prehistoric settlement on the south west slope of Brown Hill. In 1953 Archaeologist Paul Ashbee excavated a number of small cairns and a large round barrow on Brown Hill. He discovered a rock-cut burial pit beneath the barrow and very little in the cairns, concluding that they were probably clearance cairns.
A number of the earthfast stones beside the road are marked with benchmarks.
Local Archaeologist Roland Close excavated a group of hut circles beside the road. He found two large huts with paved floors, two smaller huts with central hearths and one hut with drainage ditches cutting through the two smaller huts. The main finds were nine saddle querns and some poorly-fired pottery sherds.
Close published his excavation in the Yorkshire Archaeological Journal. In his report he mentioned a permanent spring to the north of the huts, probably the primary source of water for the settlement. 
On looking through some old maps of the area I noticed that, on the 1950 OS map, a cluster of tumuli had been marked around the spring. If these tumuli were burial mounds it could mean that that spring held some significance, other than a source of water, to the people who lived there in the past.
The spring emerges from the hillside into a man-made stone-lined trough and then flows down to the Codhill Beck. There is a standing stone close to the well, the sides of the stone have been dressed, this is probably an estate boundary stone. Unfortunately the moor above the site is covered in deep heather, I was unable to find the mounds marked on the OS map.
Sources
Yorkshire Archaeological Journal Vol.39 1958 & Vol.44 1972
Old Roads & Pannier Ways in North East Yorkshire. Raymond H Hayes. 1988
Map reproduced with the permission of the National Library of Scotland
The Smell of Water 