Deloitte and Touche, 3, Lapp's Quay, Cork City, Co. Cork

The blocked carriage arch at ground floor, the ghost of loading doors running up the centre of the upper storeys, and the mismatched patchwork of sandstone and limestone across its various elevations all point to a working industrial past that has little to do with the office tenants whose name now labels it. It is the kind of building that rewards a second look: what appears at first to be simply another commercial address on a Cork street turns out to be structurally and materially a document of the city's milling trade.

The building began life in 1852 as Furlong's Mill, a five-bay, three-storey structure built gable-end to the street with a pitched, tiled roof and brick chimney stacks. Its construction mixed red sandstone and grey limestone, a combination typical of Cork's industrial buildings of the period, with rusticated limestone quoins and a plinth giving the front elevation a more formal treatment than the rubble sandstone and limestone used around the back and sides. A limestone plaque records the building date. In 1874 the mill was refitted, its original steam-powered plant replaced by the roller process, a mechanical milling method that used sets of metal rollers rather than traditional grindstones to crush grain, allowing for finer and more consistent flour. Loading doors survive at both the front and rear, on Oliver Plunkett Street Lower, along with the blocked integral carriage arches through which carts would once have passed to load and unload sacks of grain and flour. Inside, cast iron columns, limestone flagstones and timber load-bearing floors remain in much of the structure, physical evidence of how a working mill was actually built to bear weight and withstand vibration.

The building's later life has been just as layered as its fabric. An eight-bay section fronting Connell Street was converted around 1995 for use as a church, with apartments inserted above and dormer windows added to light them, while the rest of the building has passed into multiple ownership and now accommodates commercial tenants including the accountancy practice whose signage gives the place its everyday name. Little of this history announces itself from the street. The give-aways are architectural rather than signposted: the scale of the building relative to its neighbours, the arched openings with their brick or rusticated limestone dressings, the traces of the old carriage arches at front and back, and the survival, however partial, of timber windows and sheeted timber doors among the later insertions. Taken together, they mark this as one of the few remaining physical reminders of the industrial character that once defined this part of the city.