We don’t know the location of the elusive Roman settlement recorded in the Ravenna Cosmography (R.C. 31.228) as [Locus] Maponi or “[the Place] of Maponus“. There are a couple of possibilitiess:
It is possible that the Ladyward fort marks the location based on the simple premise that the fort is located near the modern town of Lochmaben, the etymology of the modern name being derived from the name of the god, Maben (= Mapon). This ancient Gaelic root is also present in the name Clochmabenstane or ‘The Stone of Lochmaben’, which is sited on the Solway Estuary just south of Gretna.
The iron-age god Maponus is often conflated with the Roman god Apollo, which is generally taken to mean that the two gods from separate pantheons shared religious practices, were patrons of the same arts and were worshipped for similar reasons. Apollo was a Roman sun god, also patron of the fine arts, poetry, music and medicine, so it is reasonable to assume that Maponus shared similar attributes. Only two dedications to Maponus have been discovered in Britain, an inscribed silver lunula from Chesterholm/Vindolanda on the Stanegate frontier in northern England, and an altarstone from somewhere on Hadrian’s Wall, here conflated with the ‘Spirit of the Emperor’ and dedicated by four Germanic troopers; no inscriptions have been recovered from the environs of Ladyward.
There are two marching camps nearby, the nearest one of 35½ acres (14.7 ha) lies less than ½ mile to the south-east at Torwood and another, larger camp of about 63 acres (c.25ha) lies about 1¼ miles due west on the opposite side of the River Annan at Lochmaben. There is also a small fortlet about a mile to the south-east, sited at the northern end of a ridge beyond the Torwood camp at Fairholm.
The Lochmaben Stone is a megalith standing in a field, nearly a mile west of the Sark mouth on the Solway Firth, three hundred yards or so above high water mark on the farm of Old Graitney in Dumfries & Galloway in Scotland. Together with a smaller stone it is all that is left of a stone circle dating back to around 3000BC. The Lochmaben stone has had a wide range of names attached to it over the last few millennia or so. Lochmabonstone, Stormont, and Old Graitney stone are amongst the most recent. In 1398 the name is ‘Clochmabenstane’, in 1409 and 1472 the name ‘Loumabanestane’ is recorded, with ‘Lowmabanstane’ used in 1485 and then ‘Loughmabanestane’ in 1494. ‘Cloch’ and ‘clach’ mean ‘stone’ in modern Irish and Scottish Gaelic respectively. In Welsh, ‘llech’ can be a flagstone, tablet or slate. The element Mabon, as in the Celtic god, is common to all of the variants and this strongly confirms this association, as well as helping with the identification of this site with the Roman site of ‘Locus Maponi’, as listed in the Ravenna Cosmography. It is also suggested that Locus Maponi means the ‘Loch’ or ‘Pool’ of Mabon and this would suggest that the town of Lochmaben is the intended named site.