The tower at Clongaddy is a windmill, or rather the shell of one, stripped of its cap and sails but otherwise largely intact to the roofline. What makes it quietly unusual is the degree of internal detail that survives: opposing doorways on the east and west, a curved recess on the north side of the ground floor, projecting steps that climb the inner wall to reach the first floor, and joists that were set directly into the stonework rather than resting on timber frames. Millstones of conglomerate stone still lie on the ground, a tangible reminder of the mechanical work once carried out inside.

The tower is three storeys high, with internal floor heights of around 2.3 metres, 1.6 metres, and 2 metres respectively. The upper floors were lit by small windows facing east, south, and north-west, suggesting the building was designed with working conditions in mind rather than purely structural convenience. The second floor had its boards set into a rebate, a shallow ledge cut into the wall to receive the edge of the flooring, a neat piece of pre-industrial carpentry that has outlasted the floor itself. The structure appears on both the 1839 and 1925 editions of the Ordnance Survey six-inch map, labelled as a windmill on both, which gives a reasonable lower bound for its age while leaving its origins somewhat open. About thirty metres to the north-west, the low remains of a rectangular building measuring roughly 13.85 metres by 4.7 metres may have served as a storehouse associated with the mill, though the walls survive only to about 1.4 metres in height. Together the two structures suggest a small but functional milling operation positioned to take advantage of the coastal winds rolling in off the Irish Sea.