WHEN I told my granddaughter we were heading north for the weekend to look at an old wall, she fixed me with the sort of withering stare reserved exclusively for grown-ups – a mixture of pity and contempt.

"Like, why?"

"Well, it will be interesting."

"Yeah, right. What could possibly be interesting about a silly old wall?"

"Well, it was built by this Roman emperor named Hadrian to keep all these Scottish barbarians out."

"And?"

Ah ... I'm afraid she had me there. I have to confess, my knowledge of Hadrian's building plans was a bit sketchy.

What little I knew came from photographs of a rough and broken stone wall climbing over hill and dale – and a scene from Robin Hood Prince of Thieves.

I now know just how sadly lacking my education was because there is far more to Hadrian's Wall than meets the eye.

In fact, it is an historic marvel, recognised as a World Heritage Site, which snakes its way across some of the most stunning, big-sky scenery this fair isle has to offer.

And despite the fact that it is knocking on for 2,000 years old and has been plundered and partially destroyed over the centuries, it is still giving up remarkable secrets.

Our journey back in time began in the tiny hillside village of Gilsland where Liam McNulty, Lauren Harrison and their delightfully eccentric sheepdog Milly invite travellers to stay at Willowford Farm, which comes complete with about a mile of The Wall running across their land.

Their website talks about a passion for local and organic food but they could just as easily substitute the word 'delicious' and save some space.

We sat down to dinner in the company of a lady from Nashville, Tennessee, and a friendly couple from Glasgow, and promptly devoured thick and creamy home made soup, venison casserole and a fresh fruit meringue, with deep satisfaction.

OK, I know we are supposed to be concentrating on The Wall, but investigating Hadrian demands long hours and lots of walking so, naturally, servicing the inner man is important.

And after a blissful sleep in a luxuriously converted barn, we were ready for the Romans.

First a quick history lesson. By the time Hadrian took the hot seat in AD117, the Roman Empire stretched from north Africa to Scotland. He decided enough was enough. Instead of more conquests Hadrian wanted to consolidate what he had.

Scotland was too much trouble, what with its harsh landscape and a population always looking for a scrap, so he drew a line across the top of the Britannia map and told his legions to build him a wall ... big enough to keep the bad guys out.

Within a dozen years, stretching from Wallsend to Solway Firth, the job was done. All 73½miles of it. Try to imagine what it must have been like...

Or better still, visit the nearby Roman Army Museum and watch an 18-minute movie called Eagle's Eye in which computer whizz-kids rebuild the wall to its 15ft high glory, an impenetrable barrier with forts and turrets which housed thousands of Roman troops and their families. Talk about the wow factor.

And it gets better. The museum is twinned with Vindolanda, site of a vast Roman fort where archaeologists spend the summer trying to expose its secrets.

What they have found so far is not only mind-boggling but of international importance.

Leather shoes and boots, jewellery and coins, weapons and tools – all vital clues to the Roman way of life 2,000 years ago.

But even those discoveries pale into insignificance when set against the world famous Vindolanda wooden writing tablets, voted Britain's "top treasures".

Somehow, because of the density of ground where they had lain for centuries, these little wooden tablets not only survived, but the words written by those Roman invaders can still be deciphered.

They include stores lists, duty rotas, requests for leave, duty officer reports and even a regimental strength report.

And most exciting of all is Claudia Severa's letter to Sulpicia Lepidina asking her to be present at her birthday party on September 11 "to make her day more enjoyable". It is the earliest surviving writing between two women in Western Europe.

It was a breathtaking find but experts at Vindolanda are still searching for more. "It could take 200 years to complete archaeological research here," staff member Fiona Watson told me.

We still had one more address to visit on our whistle stop tour. Housesteads Fort, the empire's most northerly outpost, where you can walk around the remains of the hospital, granary, commandant's house ... even the public toilets.

Perched on a wild, romantic crag with views to die for, it says everything about this wonderful, mysterious, exciting land.