Down by the North Tyne, where the river runs fast over stones under a canopy of trees, a Roman cavalry regiment once kept its horses and its very comfortable bath house. Chesters, the fort the Romans called Cilurnum, sat astride Hadrian's Wall near the village of Walwick, guarding the bridge that carried the wall across the river. It is one of the best preserved forts along the wall, with the headquarters building, the commander's house and the bath house still standing to knee or shoulder height, and the remains of the bridge abutment visible on the far bank.
The fort was preserved largely thanks to John Clayton, a nineteenth-century town clerk of Newcastle who bought up long stretches of the wall and its forts to protect them from stone robbers. The museum on site, a charming Victorian building, displays his collection of altars, inscriptions and sculptures, crowded together in the old style. Hadrian's Wall, built from AD 122 across the narrowest part of Britain, is part of the Frontiers of the Roman Empire listed by UNESCO.
The riding is one of the joys of the north of England. The B6318, the Military Road, runs west from here along the line of the wall. It was built in the eighteenth century by General Wade's successors after the Jacobite rising, partly on top of the wall itself, and it rises and falls over the crags with blind crests, sudden dips and long views. It is a fabulous road, but treacherous: the crests hide cars, sheep and walkers, the surface can be rough, and the weather changes in minutes. Summer weekends bring tourists, while autumn brings fog and wet leaves.
Hexham, six kilometres south, is the place for fuel, food and lodgings, a lively market town with a fine abbey. Acomb is a small village with a pub. The local food is hearty, from pies to fish and chips, and Northumberland lamb is excellent. A tearoom at the fort serves cakes and hot drinks, welcome after a cold ride. Walk down to the river and look across at the bridge remains; Roman engineers built them to last, and the river has been trying to wash them away ever since.