This rectangular limestone structure, measuring roughly 20.6 metres east to west and 10.5 metres north to south, stands as a weathered testament to medieval fortification in Ireland. Built from roughly coursed rubble limestone with a distinctive base batter, only the ground floor remains of what was once a more substantial building, its walls now reduced to a maximum height of five metres at the northeast corner.

The castle’s exact purpose remains something of a historical puzzle. With internal dimensions of 17.2 by 7.1 metres and walls 1.7 metres thick, it may have served as a hall-keep within a larger castle complex, or alternatively, it could represent a hall-house; a smaller type of stronghold that emerged in early 13th century Ireland. Though centuries of decay have obscured most architectural details, the faint outline of what might be a slit opening can still be traced in the centre of the eastern wall. The structure’s proximity to Lough Ree, just 20 metres from the shoreline during winter floods and 40 metres in summer, suggests it likely had strategic importance for controlling water access.

The castle’s relationship with its watery surroundings would have been crucial to its medieval inhabitants. Winter flooding still transforms the land to the west, north, and north-northeast, leaving only a narrow causeway of higher ground to the east that probably served as the original medieval access route. Given its lakeside position, the castle almost certainly maintained water access as well, and somewhere along the nearby shoreline, the remains of a medieval harbour may yet lie hidden, waiting to tell more of Corrool Castle’s story.