This earthwork fortification, likely dating from the 13th or 14th century, consists of a raised rectangular platform surrounded by a water-filled ditch, or moat. Such sites were typically constructed by Anglo-Norman settlers or wealthy Gaelic families who adopted Norman defensive techniques; they served as fortified homesteads that provided both status and security during an era of frequent territorial disputes.

The Carrowcaslan moat follows the classic design of these medieval strongholds, with its central platform measuring approximately 40 by 30 metres. Originally, this raised area would have supported a timber hall and various outbuildings, all protected by the surrounding water barrier and likely a wooden palisade. The moat itself, now partially silted but still visible as a depression in the landscape, would have been fed by local streams or springs, creating a formidable obstacle for any would-be attackers whilst also serving practical purposes such as drainage and fish farming.

Today, the site stands quietly in the Sligo countryside, its grassy banks and overgrown ditches bearing little resemblance to the bustling defended settlement it once was. Archaeological surveys have revealed traces of medieval pottery and other domestic artefacts in the vicinity, confirming its residential use. Moated sites like Carrowcaslan represent an important phase in Irish history when new defensive technologies and agricultural practices were transforming the landscape, marking the transition between Gaelic and Norman cultural influences that would shape Ireland for centuries to come.