A bawn was essentially a fortified enclosure, typically built to protect livestock and provide defence for settlers during the turbulent plantation period in Ireland. What makes this particular site intriguing is that O’Reilly appears to have adapted an existing medieval ringfort, or rath, for his purposes. Archaeological evidence suggests that Lisgannon rath, which had likely stood for centuries before O’Reilly’s arrival, was modified with the addition of a second defensive bank and a wide berm; a flat strip of land between the fortification walls; to accommodate the new bawn structure.

The original rath would have consisted of a circular earthen bank with an outer defensive ditch, or fosse, typical of early medieval Irish settlements. These earthworks served as both farmsteads and defensive positions for local Gaelic families. By incorporating the ancient rath into his bawn design, O’Reilly was effectively layering one period of Irish fortification upon another, creating a palimpsest of defensive architecture that spans from the early medieval period through to the early modern era.

Today, no visible traces of either the rath or the bawn remain above ground at Lisgannon, leaving only the historical record and archaeological surveys to tell their story. The site represents a fascinating example of how successive generations repurposed existing structures to meet their needs, with O’Reilly’s 17th-century fortification built quite literally upon the foundations of Ireland’s medieval past. This information comes from the Archaeological Inventory of County Cavan, originally published in 1995 and updated with subsequent research findings.