Hadrian’s Wall has perhaps the most single-minded personality of all the National Trails, tracing as it does the 84 miles from Bowness-on-Solway to Wallsend, which represented the north-west frontier of the Roman empire for nearly 300 years. It was built by the Roman army (the soldiers dug the ditches, quarried the stones and laid them) on the orders of the emperor Hadrian after his visit to Britain in AD 122. The Hadrian’s Wall path celebrates...