Built under royal licence by Philip Roche in the 1540s, this rectangular tower measures 10.4 metres east to west and 8 metres north to south, with a distinctive circular turret attached to its northeast corner. The castle’s dramatic positioning means the ground level on its eastern side sits at the same height as the first floor on the western side, where the land drops sharply to the river’s edge below. Though the upper storeys have long since collapsed, leaving walls that stand roughly to second floor level, early 20th-century photographs show it once rose to an impressive five storeys topped with a gabled roof.

The castle’s defensive features reveal both Scottish and English military influences of the mid-16th century. The circular turret contains three double-splayed gun ports positioned just above ground level, designed for cannon fire, whilst directly above these are seven rectangular loops angled steeply downward through the wall thickness, perfect for musket fire against attackers below. The western wall’s ground floor entrance features a pointed arch doorway with a yett hole through its northern jamb, whilst the first floor once boasted what Bennett described in 1869 as a ‘handsome bay window’, now reduced to broken remains. A single tapering corbel on the western wall marks all that survives of a bartizan that once projected from the southwest corner.

Poulnalong Castle, also known as Shippool Castle, witnessed considerable drama during its active years. In 1642, Bandon’s garrison seized the castle and reportedly killed 100 rebels there. The Herrick family later made it their residence, with Smith noting in 1750 that it had become ‘a pleasant seat with good gardens and other improvements’. However, the Herricks abandoned the castle in 1787 for a new home, and locals subsequently plundered the building for materials, making off with the fireplace and cut limestone window arches. Today, the interior lies filled with rubble from the collapsed vault, though remnants of the stolen fireplace survive at first floor level on the north wall, still bearing the crest and family arms of the Roches carved into one of its jambs.