Far, far away from civilisation, deep in the wilds of Dartmoor lies the Erme Pound. It is a collection of broken walls once used to hold animals. It may not be prehistoric but around it lie several stone rows the most famous being Stall Row, perhaps the longest on the moor. It actually crosses the River Erme jus above the pound and goes off into even wilder countryside.
To reach this point requires a stiff walk from Harford. The reward being that you can take in many antiquities along the way including following the stone row if approached from the western side of the valley.
For those wanting isolation, this is the place...especially on a wet misty day like I had!