It marks the entrance to a souterrain, one of those curious underground passages built during the early medieval period in Ireland, typically constructed from stone and used for storage, refuge, or both. The opening is sealed now, the interior inaccessible, which is not unusual; a great many souterrains across Ireland have been deliberately closed or have collapsed over the centuries, leaving only this kind of trace at ground level.

Souterrains are found throughout Ireland, but the Iveragh Peninsula has a notable concentration of early medieval remains, a reflection of the dense settlement activity that once characterised this part of south Kerry. They were generally built in association with ringforts or other enclosed settlements, dug into the earth or constructed beneath field banks, and lined with drystone walling or roofed with large stone lintels. The blocked north-western opening at Athghort is a modest piece of evidence for what was once, almost certainly, a functioning underground chamber attached to a wider domestic or agricultural complex.