County Durham lies in north-eastern England, in the heart of the former Anglian kingdom Northumbria. It has a coastline on the [[North Sea]] in the east, stretching from the [[River Tees|Tees]] estuary in the south to the Tyne estuary in the north. The River Tees forms the county's southern border with [[Yorkshire]]. [[Cumberland]] and [[Westmorland]] lie across the Pennine Hills to the west, with [[Northumberland]] lying to the north. | County Durham lies in north-eastern England, in the heart of the former Anglian kingdom Northumbria. It has a coastline on the [[North Sea]] in the east, stretching from the [[River Tees|Tees]] estuary in the south to the Tyne estuary in the north. The River Tees forms the county's southern border with [[Yorkshire]]. [[Cumberland]] and [[Westmorland]] lie across the Pennine Hills to the west, with [[Northumberland]] lying to the north. |