What remains today is a complex archaeological site that reveals the castle’s former importance as a Dillon family stronghold. The outcrop has been built up on its eastern side to create a platform, faced with a 25-metre-long stone wall that still rises to 1.75 metres in height. At the southern end of this wall, you can trace the footings of a small building, whilst to the east lies a sub-rectangular enclosure defined by more wall foundations. One particularly impressive section of wall on the eastern side of this enclosure stands 3 metres high externally and features the remains of a gun loop; a reminder of the castle’s defensive capabilities.

Historical records paint a picture of Cannorstown as a thriving estate in the early 17th century. An inquisition following the death of Robert Dillon in 1611 described the property as containing a castle, twenty dwellings, a carucate of land and a watermill, with the latter possibly standing on the site of an earlier medieval mill just 85 metres north of the castle. The estate went through several hands in quick succession: in 1621, Robert Dillon of Cannorstown surrendered his lands to the Crown, and that same year the property, including its bawn, stone hall, orchard, watermill and lands, was granted to Sir William Parsons. By 1641, however, the Down Survey records show the lands were back in the possession of another Robert Dillon, described as an ‘Irish Papist’.

Today, the site is partially obscured by ruined farm buildings dating from after 1700, which encroach upon the northern, northeastern and southern portions of the castle remains. These later structures inadvertently serve as a repository of medieval history; their walls incorporate numerous architectural fragments from the original castle, including pieces of door and window frames and quoin stones bearing the characteristic rough pock marks of medieval masonry work. These scattered fragments, built into the fabric of the newer ruins, offer tantalising glimpses of the castle’s original grandeur.