Built by the O'Heyne family, this imposing structure measures approximately 10.4 by 7.8 metres and rises to an impressive height of 18 metres, with its spiral staircase tucked into the southeast corner still providing access to all five levels. The castle's design follows the classic Type 1A tower house pattern, where the ground floor entrance leads to a lobby that cleverly branches off to both the main chamber and a smaller subsidiary chamber, whilst a doorway provides access to the corner staircase.

The O'Heynes maintained their connection to Caherelly West for centuries, with records showing various family members holding the property from at least 1599, when Tadeus O'Heyne died in possession of the castle, through to 1748. The estate changed hands several times throughout its history; by 1667 it had been confirmed to Sir William King, though the O'Heyne influence persisted in the area. The 1654-56 Civil Survey reveals that during the Cromwellian period, Teige Heyne, described as an Irish Papist, owned the property which included not just the castle but also a bawn, a mill seat, and intriguingly, a marble quarry.

The castle's defensive features speak to its turbulent past; a gunloop in the southwest corner bartizan displays both a square hole at its base and an oillet higher up, whilst the second and fourth storeys once boasted protective vaults. The fifth storey contains a room within the square bartizan, and the east wall housed a tier of subsidiary chambers positioned strategically above the entrance. Though a second tower that once stood nearby had disappeared by 1900, the main tower continues to dominate the landscape, standing as it has since medieval times when it appeared on the 17th century Down Survey map of Clanwilliam Barony, a testament to centuries of Irish castle building tradition.