The grass-covered mound rises nearly 8 metres high with a distinctive concave summit spanning 13 metres across, whilst its base stretches 40 metres in diameter. Trees dot its slopes, and though there's little evidence of the defensive ditch that typically surrounded such structures, traces of a broad, shallow fosse can still be spotted on the southeastern side where it meets the bailey; a raised rectangular platform that once formed part of the castle's outer defences.

The motte's history is deeply entwined with the Anglo-Norman conquest of Ireland. Hugh de Lacy granted the barony of Morgallion to Gilbert de Angelo before 1186, who established Nobber as the administrative centre of his manor, deliberately positioning it near the existing church. After Gilbert's outlawing in 1196, the lands passed through various hands, including Walter de Lacy's half-brother Hugh, who famously held John de Courcy, Earl of Ulster, captive here in 1201. The site witnessed an intriguing medieval transaction in 1227 when local burgesses received four townlands in exchange for constructing a causeway connecting the motte to the town, suggesting the castle's continued importance as both a defensive structure and administrative hub.

Through marriages and inheritances, Nobber passed from the FitzGeralds to the le Botiller and de Londres families, before Christopher Preston, second Lord Gormanston, acquired it in 1386. The Preston family retained ownership well into the nineteenth century, with Lord Gormanston still holding Nobber and its surrounding hamlets according to the 1654 Civil Survey. Recent archaeological investigations have uncovered tantalising glimpses of the site's past, including a two-colour medieval tile and evidence of metalled surfaces nearby, whilst the motte itself has been recognised as a monument of national importance, protected under preservation order since 1978.