Greta Bridge is a small settlement now on the south side of the A66. The name will derive from that of the bridge ahead in the image which is named on OS maps as Greta Bridge, printed in a gothic style text indicating that it's an antiquity. There's another Greta Bridge nearby, a modern structure carrying the A66.
Reminds me of a print of John Sell Cotman's water colour 'Greta Bridge' (1805) that hung on the wall of a classroom at King James I Grammar School, Bishop Auckland, in the 1940's. See http://en.wikipedia.org/wiki/John_Sell_Cotman