This castle is particularly interesting as it’s one of only a small group of tower houses in County Galway that clearly shows two distinct phases of construction. The builders first erected a compact tower block that contained all the essential defensive and circulation elements; the doorway, spiral staircase, and subsidiary chambers. Later, they added a second, larger block to house the main living chambers, effectively doubling the castle’s size.

The original tower block measured 9.3 metres north to south and 4.15 metres east to west, rising five storeys high with walls built from coursed limestone blocks and smartly dressed quoinstones. The main entrance sat centrally in the eastern wall and opened into a lobby that connected three crucial spaces: a guardroom in the northeast corner, the spiral stairs in the southeast, and likely a doorway leading west into the ground floor of the later addition. Multiple vaulted ceilings provided structural support and fire protection, covering the guardroom, the main ground floor chamber, and the space between the second and third floor subsidiary chambers. The windows progressed from simple defensive slits on lower levels to more decorative rectangular and ogee-headed single lights higher up, with a clever angle loop positioned at the northeast corner of the second floor for improved defensive coverage.

Unfortunately, time has not been kind to Seefin Castle. When inspected in 1983, the original tower block remained relatively intact whilst the second phase addition had largely collapsed. By December 2009, following reports of structural failure, inspectors discovered that the entire south wall, including the vital spiral staircase, had catastrophically collapsed along with portions of the east and west walls. The resulting rubble field extends some 10 metres from where the south wall once stood, with individual stones scattered as far as 20 metres away; a sad reminder of how even the sturdiest medieval fortifications eventually succumb to the relentless Irish weather and centuries of neglect.