Which is how I came to be on a lay-by outside Carlisle the other week, with rain seeping through the gaps in my helmet.

If Hadrian’s Wall starts anywhere, it’s at Bowness on Solway, west of Carlisle. It’s here that one of the greatest walls of ancient times plunged into the Irish Sea, having straddled the country from east to west in a near-impenetrable barrier.

A journey that would have required an armed escort in Roman times is now ‘pedallable’ in a long weekend thanks to a superbly marked cycle route.

Hadrian’s Cycleway broadly follows the course of the wall, while taking in other sites of interest and local attractions.

The beauty of the trail is that it sticks to quiet country roads, towpaths or specially designated cycle paths. And at every possible decision point a blue arrow with the route number (72) and a stylised Roman helmet points us in the right direction.

As we climb up towards the high country beyond Carlisle, we see signs of border struggles ancient and modern — stumpy watchtowers rise out of wheat fields, old farm houses sit behind walled compounds, and flags bearing St George’s cross flutter in suburban gardens.

While we can’t yet see the actual Roman wall, its shadow is all around us in the solid farmhouses and neat stone walls dividing paddocks — well-trimmed Roman blocks pillaged centuries ago.

Soon enough we’re pedalling alongside a section of the wall that runs up to Birdoswald Roman fort. It’s one of many forts and settlements along the route to have been excavated, offering a real sense of life as it was on the Roman frontier.

A few miles down the road at Vindolanda, archaeological digging is ongoing, and keen visitors can even help out.

As well as the main route, the trail map highlights day trips and diversions. We take one into Northumberland National Park — the badlands to the north of the wall. It’s beautiful, wild country, and wind-whipped sheep eye us suspiciously as a farmer on a four-wheeler putters past, a collie balancing neatly on the rear mudguards.

Over on our right rise the crags — like hills determined to be mountains, the broken shape of the wall silhouetted against the skyline.

We turn back towards them, stopping halfway up a steep climb to gorge ourselves on wild raspberries hanging heavy from the hedgerows.

The second half of the trip is a ride through time. Starting at the magnificent Housesteads Roman fort (where the 2000-year-old flushing toilets are a star attraction), we drop into the Tyne valley with its ruined castles and remnants of border wars between Scotland and England.

Then it’s a glorious riverside race along the banks of the Tyne to the docks of Newcastle, where the steel webs of Victorian bridges give way to the elegant winking eye bridge, built almost 2000 years after Hadrian’s Big Idea.

Soon we’re dipping our toes in the North Sea and planning our next trip. Sunny Italy, perhaps?

The emperor and his wall

When Hadrian became Roman emperor in 117AD, he inherited an empire that covered much of Europe, northern Africa and the Middle East.

But Rome was overstretched, embroiled in everything from an unpopular war in what is now Iraq to skirmishes on the imperial border in northern Britain. So Hadrian set about consolidating power, re-drawing borders and strengthening defences.

Hadrian’s Wall became the empire’s northern border. It regulated trade and acted as a buffer against the Picts to the north. Built from turf and cut stone, it was 6m high in places, and was fortified with 16 forts, 80 milecastles and 160 turrets.

Hadrian: Empire And Conflict, currently showing at the British Museum (www.britishmuseum.org), explores the life, love and legacy of Hadrian, and includes artefacts drawn from 31 museums.