What remains today is rather modest; a grassed over mound of earth and stone measuring roughly 7.3 metres square, with walls that once stood 1.2 metres thick. The site has long served as an informal quarry for local building projects, leaving only fragmentary sections of the original structure visible to modern visitors.

The surviving elements paint a picture of what was likely a small fortified dwelling or tower house. The eastern wall stretches for about 5 metres and reaches heights of up to 2 metres in places, whilst portions of the northern wall adjoin it. A blocked opening, possibly an original doorway or gateway measuring 1.6 metres wide, can still be traced along the southern edge of the eastern wall. Writing in 1914, local historian Neary noted the presence of two souterrain openings in the centre of the castle ruins; these underground passages, more likely cellars than true souterrains, have since vanished beneath the accumulated earth and vegetation.

Despite its diminished state, Caislean Beg remains an evocative reminder of the network of small castles and fortified houses that once dotted the Irish countryside. These structures, built by Anglo-Norman settlers and Gaelic lords alike, served as both defensive strongholds and symbols of authority over the surrounding landscape. Today, the site stands quietly in its pastoral setting, its weathered stones gradually returning to the earth from which they came.