Aerial photography taken in July 1989 captured its outline clearly: a curvilinear enclosure approximately fifty metres in diameter, defined by a raised bank and an external fosse, which is essentially a ditch dug around the perimeter to reinforce the barrier formed by the bank above it. It is the kind of feature that a person could walk past without registering as anything other than a slight rise and dip in a field.

Enclosures of this type are among the more common archaeological features in the Irish countryside, though common does not mean well understood. They are generally associated with the early medieval period, roughly the fifth to twelfth centuries, and may have served as farmsteads, places of local assembly, or locations with ritual significance, depending on their individual context. Without excavation, it is rarely possible to say which function applied in any particular case. What the Oldtown enclosure offers, in the absence of such investigation, is its geometry: the curvilinear plan and the combination of bank and fosse suggest something deliberately and carefully constructed rather than a feature that accumulated incidentally over time.