Discoveries include a settlement believed to date to the Late Neolithic or Middle Bronze Age (1600-1200 BC), as well as evidence of life in Cumbria when the A66 was a Roman road.
Stephen Rowland, project manager at Oxford Cotswold Archaeology, said: “The route followed by the modern A66 through the Eden Valley and Stainmore Pass was ancient even when the Romans formalised it with their own road, nearly 2,000 years ago.
"Significant road and river junctions and crossings are still marked by prehistoric monuments, Roman forts, and medieval castles, whilst the fertile valley has supported communities since the end of the last Ice Age."
In another location, a possible ‘grubenhaus’ - a building typically built above a large rectangular pit and associated with Early Medieval settlements - has been found.