According to local historian Twigge, the castle was constructed by Sean Mac Conmara and his son Donnchad of Magh na Neamhan, though its exact building date remains uncertain. What survives today is modest; a rectangular area roughly seven by six metres, defined by stone spreads and featuring a partial western wall that still reaches three metres in height. A single window remains visible in this wall, set within a splayed embrasure that would have allowed defenders to fire arrows whilst remaining protected. The entire structure is now surrounded by a substantial cairn of collapsed stonework, measuring approximately 30 metres across and rising up to four metres high on the eastern side.

The castle’s recorded history reveals a turbulent pattern of ownership that mirrors the broader conflicts of early modern Ireland. In 1570, it appeared in official records as ‘Ballymaslen’ under the occupation of William Neylon, whilst by 1574 it had acquired the name Castletown Nevenanagh. The MacNamaras managed to regain control sometime after 1600, but their tenure proved temporary; John Og MacNamara lost the castle following his involvement in the 1641 Rebellion, after which it was granted to two transplanters, Sir Oliver Bourke and Gibbon Fitzmaurice Fitzgibbon. By 1661, Dr John Neylon had become the tenant, and around 1712 the property was leased back to James MacNamara, whose family remained in residence until approximately 1740.

The castle’s decline appears to have been gradual rather than catastrophic. Much of its stone was repurposed for a nearby farmstead, now also deserted, which stands just to the west of the ruins. Despite its ruinous state, the site remains an evocative reminder of the complex web of Gaelic and Anglo-Norman families who contested control of Clare’s strategic locations throughout the medieval and early modern periods. The unpublished research of Risteárd Ua Cróinín and Martin Breen has documented these remains as part of their comprehensive survey of Clare’s castles and tower houses, helping to preserve knowledge of sites that might otherwise slip from memory.