Built in 1401 by Cathal, son of Tomás Ó Fearghail, this stronghold barely lasted two years before rival family members demolished it in 1403. Undeterred, Cathal rebuilt his castle in 1405, though peace remained elusive; the fortress became embroiled in a bitter feud between two branches of the Ó Fearghail descendants in 1424, culminating in its demolition by the Justiciar that same year.

The castle’s later history reflects the changing political landscape of Ireland. By 1518, the ninth Earl of Kildare was collecting rent from Kedagh mc Lyshe mic Kyady mic Thomas Ó Fearghail, who owned Barry Castle and paid the substantial sum of £20 13s. 4d. In 1621, ownership passed to Gerald McRory Farrall through a land grant that included not just the castle and surrounding lands, but also a watermill and fishing weir on the River Enny. The Down Survey map of 1655–6 marks it simply as the ‘Old Castle’, with the mill shown to its south.

Today, visitors will find only a grass-covered mound of collapsed rubble, roughly 19 metres north to south and 15 metres east to west, rising about 2 metres high. The original castle plan has been completely obscured by centuries of decay, though keen observers can spot two courses of external stone facing on the north wall. Several gaps in the rubble mark where locals once quarried stone for other building projects, and the site sits within what may have been a larger moated complex, adding another layer of intrigue to this forgotten fortress.