Known locally as O'Conor Faly's or Croghan Castle, this rectangular fortified residence would have commanded extensive views across the surrounding lowlands in every direction except north, where Croghan Hill itself rises up, topped by its ancient church and deserted medieval village. Today, only the northwest and southeast corners of the castle survive to battlement height, making it challenging to fully appreciate the structure's original imposing presence.

The surviving corners offer tantalising glimpses into the castle's construction and defensive capabilities. The northwest corner features modernised battlements containing bricks, with a chimney connected to a second-floor fireplace that measures an impressive 2.1 metres wide and 3.8 metres high, constructed with punch-dressed stone. The southern corner tower shows evidence of a base batter on its south-facing wall, though this may be a later addition. A wall attached to the west side of this tower contains two openings that appear to be destroyed windows, likely part of the original castle structure. Both towers retain evidence of a wall walk inside the battlements, suggesting the tower house originally stood three storeys high with external dimensions of approximately 28.6 metres north to south and 13.5 metres east to west.

Archaeological testing conducted in 2004 around the site's modern piggery facilities revealed nothing of significance, though the castle itself speaks volumes about late medieval fortified living in Ireland. The presence of brick alongside traditional limestone rubble, combined with large windows unsuited for defence, indicates this was a well-appointed residence built for comfort as much as security. First documented by antiquarians in the 19th century and surveyed multiple times since, these fragments of masonry continue to hint at the power and prosperity of those who once called this strategic location home, even as farm life carries on around them.