Swale, and reaches the village of Keld. From Keld the path crosses the route of the Coast to Coast Walk, then ascends a side valley known as Stones Dale to reach Tan Hill and its isolated inn at the northern boundary of the National Park. North Pennines At Tan Hill the Pennine Way enters the North Pennines AONB and follows moorland tracks to the isolated settlement of Sleightholme, where the route divides. The main route heads directly north across the moors, crossing God's Bridge and passing beneath the A66 road in a tunnel. The alternative route enters the town of Bowes and rejoins the main route at Baldersdale. From Baldersdale the trail crosses Lunedale and descends to the small town of Middleton-in-Teesdale. From Middleton the path ascends Teesdale on the right bank of the River Tees, below the village of Holwick. It passes the waterfalls of Low Force and High Force, and reaches the scattered settlement of Forest-in-Teesdale. Further up the Tees, the path climbs beside the waterfall of Cauldron Snout below the dam of Cow Green Reservoir. The trail then ascends the gently rising side valley of Maize Beck to reach High Cup Gill, one of the most photographed areas on the Pennine Way. From High Cup the trail descends to the village of Dufton. From Dufton the Pennine Way climbs back up the fells, passing in turn the summits of Knock Fell, Great Dun Fell, Little Dun Fell and finally Cross Fell, at the highest point on the entire path. Here, walkers can face tricky conditions in bad weather as a result of the Helm Wind which sweeps down the south-west slope of the escarpment. A long descent follows to the valley of the South Tyne at Garrigill. The trail then keeps close to the river to enter the town of Alston. The trail continues down the valley of the South Tyne, past the Roman fort of Whitley Castle, to Slaggyford and Knarsdale. Above the village of Lambley the trail leaves the valley to cross more moorland to the A69 near the village of Greenhead. Northumberland National Park and the Scottish border Outside Greenhead the Pennine Way passes Thirlwall Castle on Hadrian's Wall. For the next the route coincides with the Hadrian's Wall Path, following the wall closely past Once Brewed to Rapishaw Gap, west of the Housesteads Roman Fort. From the wall the trail heads north through