The ivy-clad ruins sit strategically between a holy well and a motte, within the bounds of what was once a medieval borough. The main rectangular hall stretches approximately 18.75 metres east to west and 14.8 metres north to south, constructed from roughly coursed sandstone blocks with a subtle batter at its base. Though the corner quoins have long since been robbed, the structure retains fascinating medieval features including five narrow slit windows; three pierce the north wall whilst single examples survive in the west and south walls, each set within embrasures covered by plank-centred rounded vaults.

The original hall was later expanded with rectangular projections at both the eastern and western ends, suggesting evolving defensive and domestic needs. The eastern addition, now bisected by a farm track that has left its east wall standing in isolation, appears to have served as an entrance porch with its own doorway in the south wall, evidenced by a surviving draw-bar socket. The western projection, the only portion still reaching first-floor level despite being choked with collapsed masonry, seems to have functioned as a service tower with a vaulted ground floor and a slit window at the upper level. The main entrance in the centre of the hall’s east wall retains its draw-bar socket, though 19th-century gate piers have replaced the original door, and the base of a spiral staircase survives just north of this doorway.

Historical records first mention a castle at this location in the 14th century, and by 1610 it was already being referred to as the ‘old castle’ of Castletown. Local historian Lewis suggested in 1837 that a castle was built here by MacEneiry in 1349, though he provided no source for this claim. It’s possible that this structure succeeded the nearby motte and may have been constructed by Thomas de Clare. The building’s conversion to agricultural use in the 19th century, including its unfortunate service as a slurry pit and the insertion of partition walls, has obscured some of its medieval character, but enough survives to tell the story of this once-important fortified residence.