That last detail is not vandalism but practicality: cattle had been sheltering inside the roofless tower, and the infilling was a straightforward solution to a recurring problem. The mill is built of randomly coursed masonry, meaning the stones are laid without uniform horizontal courses, giving the wall its rough, irregular texture, and it sits at the centre of a circular earthwork rampart that encircles it like a collar.

An external plaque records that the mill was built by Edward and Mary Walsh of Boranstown in 1736, and by 1760 it was prominent enough to be marked on John Rocque's detailed map of County Dublin, labelled simply as the Windmill of Garristown. Inside, a second plaque on the east wall has had its names deliberately removed by pocking of the stone, which suggests some later falling-out with whoever commissioned it, and above that a stone is marked with the year 1827. The enclosing rampart is a curiosity in itself. Writing in 1939, Morris described it as roughly 275 yards in circumference, standing two feet high on the inside and between five and eight feet on the outside, and he noted that the quarrying of stone to build the mill had actually cut into it, proving the earthwork was already there when construction began. Whether the rampart is ancient or was raised at the same time as the mill remains unresolved, though one interpretation, supported by comparison with the windmill at Skerries, is that it was built specifically to keep cattle away from the turning sails.

The mill sits on the Ordnance Survey six-inch map of 1837 surrounded by its earthwork, with a drying kiln and quarry marked just to the north and a pathway running through the eastern side of the enclosure on a north-south axis. The site is accessible and the exterior can be examined closely, including the plaque inscription set into the stonework. The commanding elevation means the surrounding landscape of north Dublin and beyond is visible in most directions, which helps explain why a commercial mill was placed here in the first place and why the spot was likely in use, in one form or another, long before Edward and Mary Walsh ordered the first stone to be laid.