The castle was once the residence of the Fitzmaurice clan, Lords of Kerry, and originally stretched from its current position all the way to the banks of the River Feale, though that section has long since been demolished. What remains today dates primarily to the 15th century; two limestone towers connected by a central wall and high arches, similar in design to Bunratty Castle in County Clare. The structure features distinctive defensive elements including a large pointed arch that projects from the wall, creating a machicolation above the door from which defenders could rain missiles down on attackers below.

The castle’s turbulent history reflects the broader struggles of medieval and early modern Ireland. Documentary evidence suggests fortifications existed here from the Norman arrival in North Kerry, with Maurice Fitzmaurice constructing a castle around 1270. The Annals of the Four Masters record that in 1582, Mac Maurice himself destroyed several settlements including Listowel when his territory was plundered. The castle’s most dramatic moment came in November 1600 during a three week siege by Sir Charles Wilmot, temporary commander of the English army in Munster. After an initial attempt to mine under the castle walls was foiled by flooding, Wilmot’s forces successfully undermined the foundations, forcing the eighteen defenders to surrender. Nine were immediately hanged, matching the number of English soldiers lost during the siege, whilst the remainder were executed on orders from the President of Munster.

The architectural details reveal sophisticated medieval defensive planning. Both towers feature splayed windows at ground level, with three pointed window loops on each tower surrounded by cut limestone blocks. The central wall contains multiple defensive positions; five square headed slits provide covering fire angles for the main door, whilst the door itself sits within a large rectangular recess that also incorporates a round headed window loop. Though primarily defensive, these narrow openings also served to provide light and ventilation to the interior spaces. Standing roughly 15 metres high, the castle towers still dominate this corner of Listowel, situated just 25 metres from the River Feale with the medieval church and graveyard 600 metres to the northeast, continuing to mark the landscape as they have for over 500 years.