No earthwork, no bank, no hollow in the ground gives any hint that something was once here. The site is known only because a cartographer recorded it, and because the archaeological record has kept that observation alive long after the landscape itself moved on.

The 1842 Ordnance Survey six-inch map, one of the most detailed surveys of nineteenth-century Ireland, shows a hachured semi-circular arc sitting alongside a north-east to south-west laneway, with a diameter of around fifty metres. That shape would have been a rath, the Irish term for a ringfort, which is a type of enclosed farmstead typically dating to the early medieval period, roughly the sixth to twelfth centuries. These were the commonplace domestic settlements of their time, defined by one or more earthen banks and ditches enclosing a space used for a farmhouse and outbuildings. The Carrignavar example was not unusually large, but it was substantial enough to leave a clear impression on the map. By the time anyone thought to record it archaeologically, even that impression had gone. The site is also associated with a possible souterrain, an underground stone-lined passage typically used for storage or refuge, though no trace of that either is visible today.