The castle, which appears on early Ordnance Survey maps from the 19th and early 20th centuries, was likely built by either Seán or Eoghan McNamara, though precise details about its construction have been lost to time. The site takes its name from the surrounding Cullaun townland, with Lough Cullaunyheeda lying immediately to the east.

The castle’s documented history provides glimpses into the complex web of Irish noble families during the Tudor period. In 1551, Murrough O’Brien bequeathed the castle to his son Donough O’Brien of Lemeneagh Castle in his will. However, the fortification’s active life proved relatively short; by 1618, it had already fallen into ruin. An inquisition from that year records its transfer from Donough O’Brien, 4th Earl of Thomond, to Maurice Mulconrey and his heirs, described even then as a “ruined castle.”

Modern agricultural activities have significantly impacted the site over recent decades. During land reclamation work in 1992, a substantial portion of the mound was destroyed, though the disturbance revealed architectural fragments including quoins, window jambs, and a sillstone with a pivot hole. By 2004, observers noted what appeared to be part of a collapsed ceiling vault amongst the debris, whilst the mound itself measured approximately 15 metres in diameter and stood 3 metres high. A more recent inspection in 2019 found that these loose stones had been removed, leaving only the grassed-over earthwork as testament to this once-proud fortress. The site has been under a preservation order since 1992, protecting what remains of this fragment of Clare’s medieval heritage.