Near the townland of Killahan in north County Kerry, there was once a large circular earthwork of the kind known as a rath, a type of enclosed farmstead built during the early medieval period, typically defined by one or more earthen banks and ditches. It is the sort of site that, had it endured, might have drawn quiet curiosity from walkers cutting across the fields. Instead, it exists only as an absence, a place whose coordinates outlasted its fabric.

The enclosure was recorded on the Ordnance Survey map of 1841 to 1842, positioned to the west-northwest of the Tonaknock stone cross. That reference point, a fixed landmark in the landscape, was enough to anchor its location for nineteenth-century cartographers. But by the time the 1916 edition of the OS map was produced, the site had been dropped from the record entirely, and no physical trace of it survives today. The intervening decades had apparently seen the earthwork levelled, most likely through agricultural improvement, a process that quietly erased many such sites across Ireland as land was drained, ploughed, and consolidated during the nineteenth century.