Milefortlets are the small, easily overlooked members of the Roman frontier family. On Hadrian's Wall itself they stood every Roman mile, with a gate through the wall and a tiny garrison, and when the Romans extended the system along the Cumbrian coast, to guard against landings from across the Solway, they built milefortlets and watchtowers all the way down the shore. Number 21 stood at Swarthy Hill, on a low rise by the sea north of Maryport, and excavations here showed a small rectangular fortlet with timber buildings inside and a ditch around.
Little can be seen above ground today, and that is part of the point. The frontier here was a line of attention rather than a line of stone, and you have to imagine a soldier on a tower looking out over the same grey water as you. On a clear day the view over the Solway takes in the Scottish hills and the long silhouette of the Galloway coast, and in the evening the sun drops behind them in a long gold streak. Fields behind the cliff are grazed by sheep and cattle, and skylarks sing over the grass in spring.
The roads here are minor, narrow and exposed. The coastal route is gentle, without hills, and in good weather it is a relaxed ride, but wind pushes hard across the open fields, and farm traffic is common. Mud on the road near field gates is a hazard, and the roads often have soft edges. Keep the speed low and watch for walkers on the coast path, which runs near the site.
Dearham is a village of under two thousand people, with a small shop and a pub, and Maryport, five kilometres away, has the fuel, bakeries and cafes. It is worth combining this stop with the Roman fort and museum in Maryport itself, which tells the wider story. Go in late afternoon in spring or autumn, when the low sun picks out the shape of the ground and the whole coast feels very quiet.