This square tower, with its subtly rounded corners, rises approximately 7.5 metres from the ground and was built from roughly coursed red conglomerate stone, mortared together but left undressed except for the limestone surrounds of its pointed arch doorways. The walls, measuring a substantial 2.5 metres thick, enclose an internal space of 3.7 by 5.5 metres, creating a compact but formidable structure that once served as both residence and fortress.

The tower's defensive features are particularly well preserved, showcasing the practical concerns of its medieval builders. The original entrance, positioned in the north wall, leads to a clever mural staircase that winds eastward through the thickness of the wall itself. The ground floor, protected by a sturdy barrel vault, features defensive loops of varying designs; splayed ones pierce the north and west walls, whilst simpler loops appear in the east and north walls, with one north wall loop opening from a rectangular recess. Above, the first and second floors each contain garderobes built into the south wall, directly opposite the entrance, demonstrating that even defensive structures required basic amenities.

Later additions tell their own story of the site's evolution through the centuries. A rectangular tower was subsequently attached to the southwest corner, whilst the entire tower house was eventually incorporated into a larger residence to the west, now sadly ruined, which likely dates from the late seventeenth or early eighteenth century. This layering of architectural periods, from medieval fortification to early modern manor house, makes Castleroe West a particularly intriguing example of how Irish castles adapted to changing times and needs, transforming from military strongholds into more comfortable, though still imposing, family homes.