Just over the brow of Swarthy Hill, overlooking the Saltpans, you will find an excavated Roman Milefortlet.
When Emperor Hadrian visited the boundaries of the Roman Empire in 122AD, he ordered the building of border defences on a massive scale. Hadrian's Wall is his finest achievement and is a testament to the might of the Roman Empire. However, contrary to popular belief, Hadrian's Wall did not solve the Romans' problem of border security. In areas such as West Cumbria they had a particular problem in that the coastline was in close proximity to the Scottish border. It would take little enterprise for their enemies to bypass the Wall and raid the Cumbrian coast. The stretch of coastline north of Maryport, just south of Hadrian's Wall, was particularly open and exposed to an attack.
To combat this weak link in their defences, the Romans built a series of milefortlets, which linked with Hadrian's Wall. These were interspersed with small towers, although, unlike Hadrian's Wall, they were not connected by a continuous stone or turf barrier.
The full extent of Roman defences along the Solway Coast is unknown; there are remains of milefortlets between Port Carlisle in the north and south of Maryport. In addition there were some larger forts and garrisons in the area, most notably the settlement of Maryport, which boasts some of the most exciting archaeological finds in Britain.
Emperor Hadrian reigned between 122AD and 140AD, after which time the West Cumbrian milefortlets appear to have been abandoned.
As you look around the site of the milefortlet, excavated between 1990-1991, you may notice its placement just off the brow of the hill. This could be due to the Romans' insistence on placing the fortlets exactly one Roman mile apart, rather than moving the site 20 yards for the best possible views across the Solway.