This oval earthwork, measuring roughly 63 metres north to south and 50 metres east to west, appears as a distinctive cropmark in aerial photographs; its wide fosse, or defensive ditch, still visible after hundreds of years beneath the plough. The enclosure was first spotted in Google Earth Pro imagery from July 2018 by researcher Jean-Charles Caillère, who identified the telltale signs of archaeological features hidden just below the surface.

The tower house known as Ballyloo Castle sits on the eastern edge of this enclosure, a strategic placement that would have allowed its occupants to survey the surrounding countryside whilst maintaining a secure defensive position. The fosse that defines the enclosure’s boundary measures between four and five metres wide, a substantial earthwork that would have presented a formidable obstacle to any unwelcome visitors. Historical maps from the Ordnance Survey’s second edition show a stream running along the western edge of the site, which likely fed water into the defensive ditch, creating an additional barrier against attack.

Archaeological evidence strongly suggests this enclosure functioned as a bawn; a fortified courtyard typical of Irish tower houses from the late medieval and early modern periods. These defensive enclosures served multiple purposes, providing protected space for livestock during raids, accommodation for tenants and workers, and an outer line of defence for the tower house itself. The Ballyloo site represents a well-preserved example of this distinctively Irish form of fortification, its outline still clearly etched into the landscape despite centuries of agricultural activity.