First documented in detail during the 1940s by archaeologist O’Kelly, this rectangular earthwork measures approximately 26 metres from north to south and 18 metres from east to west. The structure consists of a stone bank that once stood between 2 and 3 metres thick, though centuries of weathering have left it considerably collapsed, particularly along the eastern side where the original entrance has been completely obscured.

What makes this site particularly intriguing is its simplicity; unlike many contemporary fortifications, Kilderry lacks a fosse, or defensive ditch, suggesting it may have served a different purpose than purely military defence. The monument likely dates to the medieval period when such moated sites were commonly constructed by Anglo-Norman settlers and wealthy Irish families as fortified homesteads. These earthworks typically enclosed timber buildings and provided both status and security to their inhabitants.

Though dense vegetation had overtaken the site by the time of O’Kelly’s 1943 survey, modern technology has breathed new life into its study. Digital Globe aerial photographs now clearly reveal the monument’s outline from above, allowing researchers to trace the full extent of the earthwork despite the heavy overgrowth at ground level. This bird’s eye view has proved invaluable for understanding the site’s original layout and its relationship to the surrounding landscape, information compiled by archaeologist Caimin O’Brien in February 2020 for ongoing heritage documentation efforts.