The structure takes the form of an impressive oval mound, measuring 22 metres from north to south and 15 metres from east to west, rising to a height of 6 metres. Its round summit and steeply sloping sides are characteristic of the motte-and-bailey castles introduced to Ireland by the Anglo-Normans in the late 12th century.

These artificial mounds were typically constructed by piling earth and stones into a steep-sided hill, then crowned with a wooden palisade and tower. The motte at Ballymadrough would have served as the last line of defence for its medieval occupants, offering commanding views of the surrounding countryside whilst providing a formidable obstacle to any would-be attackers. The steep slopes, still clearly visible today despite centuries of erosion, would have made any assault on the summit extremely difficult.

Today, the motte stands as a tree-covered reminder of Dublin's medieval past. The trees that now grow across its surface add to its picturesque quality whilst helping to preserve the earthwork from further erosion. Though the wooden structures that once topped it have long since vanished, the mound itself remains remarkably intact; a testament to the engineering skills of its builders and an intriguing piece of Ireland's Norman heritage hiding in plain sight.