The main site consists of a ringwork, a type of medieval earthwork fortification, which once enclosed what appears to have been a second castle. Whilst the primary castle site is well documented, this additional fortification remains something of an enigma; only a single reference from 1607-08 mentions its existence, leaving historians to piece together its story from scant evidence.

The only visual confirmation of this second castle’s location comes from the 1839 edition of the Ordnance Survey 6-inch map, which places it within the ringwork and adjacent to the main castle site. Today, visitors to the area will find no visible remains of any structure at ground level, making it a true ghost of Ireland’s medieval past. The Down Survey barony maps, created in the 17th century as part of the first systematic mapping of Irish lands, provide additional historical context for understanding the site’s layout and importance during earlier periods.

Archaeological surveys have catalogued these sites as WX039-028001 for the ringwork and WX039-028002 for the castle site, forming part of the comprehensive Archaeological Inventory of County Wexford published in 1996. Whilst the physical structures may have vanished, their documentation ensures that Great Island’s dual fortifications remain part of the historical record, offering insights into the defensive strategies and settlement patterns of medieval Wexford.