Seatsides is a name on a map of fields, a spot where a Roman temporary camp is visible only as a faint square in the grass when the light is low. These camps were put up by marching armies, each night, with a ditch and a bank thrown around a regular rectangle, and some of them in the north of England survive as earthworks nearly two thousand years later. This one lies near Haltwhistle, in the Tyne Gap, the low pass that cuts between the Pennines and the Cheviot hills and has been the natural route from east to west across northern England since before the Romans.
The wall itself runs close by, along the edge of the Whin Sill crags at Walltown, where the Roman Army Museum tells the story of the soldiers who lived here. Haltwhistle claims to be the centre of Britain, a boast you can spot on shop signs, and it is a small, attractive town of stone houses on the South Tyne. Nearby Greenhead and Gilsland mark the point where the wall runs into Cumbria. The land is a mixture of rough grazing, wet pasture and sudden rocky outcrops, and curlews and lapwings call in the spring.
The roads here are open and often exposed, rising and falling over the ridges. Wind and rain sweep across the high ground, and sheep and cattle are regular obstacles. The A69 is a fast dual-carriageway-style route carrying plenty of lorries, while the smaller roads up toward the wall, notably the old military road, are much more fun. In winter the higher sections can ice up, and snow sometimes closes them.
Haltwhistle has a few thousand people and enough shops and cafes for a break, and it also has fuel, though it is wise to top up in Hexham or Carlisle before heading into the quieter hills. Pack a waterproof, because the weather here changes quickly. The best time for the wall country is late spring or early autumn.