This lofty tower, rising 18 metres high from its rocky foundation, was once a stronghold of the powerful Earls of Desmond. Though only the northern half of the structure survives today, what remains reveals a formidable five-storey tower house that measured approximately 10.5 by 9 metres internally, with walls nearly 2 metres thick. The castle's design follows a typical late medieval Irish pattern, with its entrance positioned in one of the long walls near a corner, leading to a lobby within the wall's thickness and a spiral staircase that provided access to the upper floors.

The castle's turbulent history reflects the broader struggles of 16th and 17th century Ireland. In 1573, Gerald, Earl of Desmond, made a dramatic escape from the Tower of London and, reaching his lands in just three days, promptly expelled English forces from what may have been this very castle. The fortress continued to play a role in the Desmond rebellions until the earl's eventual downfall. By 1650, during Cromwell's conquest of Ireland, Sir Henry Waller captured and dismantled Shanpallas, effectively ending its military significance. The property subsequently passed through various hands, from the Duke of York to the Bury family, ancestors of the Lords Charleville.

Beyond the main tower, remnants of the castle's defensive complex still tell their story. A round turret with spiral stairs once connected to a sallyport near a pool, whilst traces of an outer bawn wall, originally enclosing a courtyard roughly 55 metres square, can still be discerned despite later farmbuildings encroaching on the space. Near the tower stand the impressive remains of what's known as "the Court", with walls still reaching 9 metres in height. These scattered elements paint a picture of what was once a substantial fortified residence, strategically positioned to control the surrounding landscape and waterways of medieval Limerick.