Where Dere Street, the great Roman road north from York, met Hadrian's Wall, the Romans built a gateway, and a mile or so west of it they placed the fort of Haltonchesters, known to them as Onnum. Today the site is a grassy field on the edge of the Military Road above the Tyne valley, with little to see beyond the faint outline of ramparts. But the setting is the thing: rolling Northumberland farmland, stone walls, the Tyne below, and on a clear day views far to the north and south.
The junction of the old Roman road and the Wall is marked today by the Stagshaw roundabout, at Port Gate, where the A68 crosses the B6318. A few miles south, in the valley, lies Corbridge, which was a major Roman supply town behind the frontier. The excavated remains there, with granaries, a fountain house and streets, give a sense of the scale of the operation that kept the Wall supplied. Corbridge itself is a lovely stone village with good cafés, a bridge over the Tyne and an old fortified vicar's tower. Nearby Aydon Castle is a fortified manor house that survived the border wars almost intact.
The riding is excellent. The Military Road, the B6318, runs west from here along the line of the Wall, rising and falling over the ridges in long straights with sudden crests and dips. It was built in the eighteenth century, after the Jacobite rising, to move troops quickly across the country, and for long stretches the road was laid directly on the Wall's foundations. It is a thrilling road, but the blind summits can hide oncoming traffic, so stay alert. The A68 north towards Scotland is also a classic, a roller coaster of steep climbs and dips through open moorland.
Northumberland weather can be wild: wind, rain and low cloud are common, even in summer. Sheep wander onto the roads, and farm traffic is frequent.
Corbridge and Hexham, both close by, have fuel, food and everything else. Hexham has a fine abbey and a market square. The pubs in the area serve good local food. Stop at the fort site, look north over the empty country, and imagine the soldiers who stood guard here, far from home at the edge of the empire.