On 13 March, a line of light will blaze along Hadrian's Wall from coast to coast, Adrian Mourby and his son walked the route

John and I arrived at Arbeia Roman Fort, hot and close to an argument.

The idea had been to get a pre-walk image of Britain's Roman coastline because the actual point where Hadrian began his wall, Newcastle upon Tyne, had long ago buried all traces of Pons Aelius, the original Roman fort, under a Norman castle. We do these father/son trips from time to time. It's proved a good mixture of exercise, travel and family bonding. Only this time the bonding had been severely tested by my dozy son leaving his backpack on the 15.03 to Edinburgh. Maria, our taxi driver, was wonderful dropping us at Arbeia and then zooming back to Newcastle station to see if she could track it down.

I had an ulterior motive for this trip. In a couple of weeks , a spectacular line of light will illuminate the entire coast-to-coast length of Hadrian's Wall for one night only. I wanted to preview the beginning of the route while introducing John to what the Roman empire had done for us.

Our starting point, Arbeia, was the military granary that supplied the wall. It's been partially reconstructed in open ground, a fortified stone gate with ramparts amid the narrow terraced streets of South Shields.

"I really can't believe it!" I muttered, a remark that Val, our guide, took as a reaction to the building's remarkable authenticity. Cheerily she led us through the reconstructed barracks on other side of the dig. Here we saw how the commanding officer and his wife would have lived in tall rooms, painted in bright Mediterranean hues. Meanwhile his troops slept in wattle-and-daub cubicles dominated by three-up three-down bunks. According to an inscription they were probably from the Tigris region, which is how this fort got its name. "Arbeia means place of the Arabs," Val explained to John, smiling and nodding now. My 19-year-old has a remarkable ability to get over my blowing up at him and, as ever, I soon forgot the backpack and was enjoying Arbeia too.

"You can tell where the grain was kept," Val said, "because grain is very, very heavy when stored. Any foundations that have been buttressed were the granaries." There were a lot of them; feeding legionaries from coast to coast must have been a huge job.

Our own provisioning came later once I'd received a call from Maria's boss saying that John's rucksack was in the lost-and-found at Edinburgh station, and had to be collected. By this time we were checking into the Hotel du Vin which overlooks the Tyne and the new Gateshead Millennium Bridge.

"You're going up to Edinburgh tomorrow first thing," I told my son,"before we start the walk." John nodded. But then David, the deputy manager, offered to go as he had a friend he wanted to catch up with in Edinburgh. I tried to insist that this was beyond the remit of any hotelier, and yet I was tempted. I had more confidence in a stranger getting there and back in time for us to start walking than in John.

We celebrated by going out to eat pizza in Newcastle, a city I last saw in 1983. I've never been quite so disorientated. Much that I remember was still there but it didn't seem to be in the same order. The next day we set off from Pons Aelius and headed west. I checked my watch. "1.15!" I declared slapping John on the back. By 1.30 we were sheltering from a vindictive thunderstorm under one of the Tyne bridges. Half an hour later we emerged and headed along the Hadrian's Wall Path, which is really the northern embankment of the Tyne.

The wall itself lies under the dull suburbs of Benwell and Denton. No one would want to walk those, so the map sends you along empty quaysides and through a new business park. It takes a while for Hadrian's Wall to start resembling those dramatic images of Steel Rigg, Housesteads and Cuddy's Crag. I dealt with a solid day of disenchanted boy before leaving him heading towards the aptly named village of Wall. As we parted John waved his walking stick cheerily. This was the part of the walk he had been looking forward to.

Unfortunately his first solo day ended with the police looking for him as he was two hours late and had not switched on his mobile phone. The second day he lost his phone. By the third day a pinched a nerve meant he was having difficulty carrying his backpack and the kind owner of the next hotel collected him by car.

For the rest of the week I was amazed by the kindness of people: the hotel receptionist who drove John and his arm to the doctor; the lady who found his phone and hand-delivered it to the next B & B; the hoteliers who arranged for Hadrian's Haul – a great scheme – to transfer John's rucksack by van (£5 a day – a bargain); the people who made him sandwiches; the fellow travellers who put him right when lost, those who mailed back the heavier items John chose to leave behind.

Over the week my son discovered Hadrian's Wall and I rediscovered how generous people can be to strangers.

Compact Facts

How to get there

Adrian and John travelled to Newvastle on Cross Country Trains (0844 811 0124 crosscountrytrains.co.uk) and stayed at the Hotel du Vin & Bistro, Newcastle upon Tyne (0191-229 2200; hotelduvin.com/ newcastle) where double rooms with breakfast cost from £99.

Further information

For details on walking Hadrian's Wall and the Lighting of the Wall festival, visit hadrians-wall.org