This subcircular earthwork measures approximately 48 metres northwest to southeast and 41 metres northeast to southwest, surrounded by an impressive defensive system. The site consists of an inner earthen bank standing 3 to 4 metres high on its exterior, separated from an outer bank by a deep fosse, or defensive ditch, that’s about 2 metres deep and up to 11 metres wide at its top. The entrance, marked by a 3 metre wide causeway, faces north-northeast, and the entire complex spans an impressive 73 metres at its widest point.

The site’s interpretation has sparked considerable academic debate amongst historians and archaeologists. Some scholars, including Graham and Sweetman, have identified it as a ringwork castle, a type of Norman fortification consisting of earthen banks and ditches rather than stone walls. Local historical records suggest this could be the castle of Onagh, constructed in 1236 and subsequently destroyed by Áedh O’Conor during territorial conflicts in 1270. However, other researchers like O’Conor propose an alternative theory: that the earthworks began life as a rath, an earlier Irish ringfort, which was later refortified and adapted for defensive purposes.

Adding another layer to the site’s rich history, the ruins of a late 16th or early 17th century house stand within the interior of the earthwork. This structure likely represents a later phase of occupation, when the medieval defences were repurposed to protect a more modern dwelling. Today, grass covers much of the site, with only traces of the original facing stones visible along the banks, whilst the outer defensive bank has been partially incorporated into a modern road bank on the northeastern and southeastern sides.