The castle likely stood on the summit at the northeastern end of a flat-topped ridge that stretches from northeast to southwest, though pinpointing its precise position has proved challenging since all the surrounding field boundaries have long since been removed. Today, visitors to the area will find no visible remains at ground level; instead, a large concrete shed and silage pit occupy the southeastern slope just below where the fortress once commanded the landscape.

Historical records provide tantalizing glimpses of this lost stronghold. The first edition Ordnance Survey map from 1840 marked the site as 'Castle (in ruins)', suggesting that some remnants were still visible in the mid-19th century. By the time of the 1904 edition, however, the notation had changed to 'Castle (site of)', indicating that even these ruins had vanished. The Civil Survey of 1654-6, conducted during the Cromwellian period, simply recorded it as a 'Castle', offering no details about its size, layout, or the family who built it.

The disappearance of Knockanroe Castle speaks to a common fate for many of Ireland's lesser-known medieval fortifications. Whether it was deliberately demolished for building materials, gradually succumbed to centuries of weathering, or was simply abandoned and left to decay, its story has been largely erased from the landscape. What remains is an absence; a ridge that once bore a castle, now marked only by modern agricultural structures and the brief mentions in old surveys and maps.