Grenan Flour Mill, Mill Street, Thomastown, Co. Kilkenny

The window openings run along its length with a regularity that borders on the monotonous, small square and camber-headed openings repeated storey after storey, and it is precisely this discipline of pattern, combined with the sheer mass of the building, that makes it such a commanding presence in the landscape around Thomastown. It has since found other uses, but the original composition survives largely intact, and with it the sense of what an eighteenth-century industrial powerhouse was built to project.

The mill dates to around 1775, though it likely stands on the site of, and incorporates fabric from, a much earlier operation. Tradition holds that the complex began in the late seventeenth century as one of three flour mills built for the Pilsworth family by Dutch engineers, part of a wave of Continental expertise brought to Ireland to improve milling technology. Whatever survived of that 1690s structure was apparently absorbed into the later rebuilding, making the present mill a layered object even before considering its later alterations. The complex was still working as late as 1949, a long working life for a building of this scale, and it supported much of the surrounding agricultural economy for generations before eventually being adapted to other commercial purposes. Around the main block cluster the supporting structures typical of a mill of this size and period: a waterwheel house to the north, now disused and re-roofed in corrugated iron since the 1950s, its wheel race still crossed by a stone culvert with a segmental arch; a two-storey outbuilding, partly refenestrated in the 1970s; and a gateway with limestone piers marking the approach, its gates long since removed.

The building's rendered walls, ruled and lined in the manner common to the period, are unpainted except at ground floor, and the small windows, many without sills, use concealed brick dressings rather than stone, a detail easy to miss unless you are looking closely at how the openings are finished. The cut-limestone stage rising at the crossing of the U-plan, with its own hipped roof, marks the point where the mill's different ranges meet, and is worth pausing at if only to appreciate how much of the original roofline and detailing, down to the cast-iron rainwater goods and iron tie bars holding the walls together, has been allowed to remain rather than being stripped away for its new function.