112 Irish Street, Downpatrick, Co Down, BT30 6BT

112 Irish Street, Downpatrick is a fine three-storey Georgian terrace townhouse dating from around 1790, with a basement. It stands at the south end of the east side of Irish Street, with its rubble stone façade facing west.

The front façade is asymmetrical. A distinctive double flight of stone steps with wrought iron railings rises to the entrance. The front door is panelled and set within an elliptical arch-headed opening, accompanied by a fanlight with 'petal' tracery, sidelights with three panes each, and timber pilaster jambs. To either side of the double stair are crudely blocked basement windows. To the left of the door sits a sash window with Georgian panes (6/6 lights); to the right is another 6/6 window and, at the far right, a short single stair leads to a sheeted side door providing access to a side entry and rear yard. The first floor contains four evenly spaced sash windows, slightly shorter than those on the ground floor. The second floor has four similar windows, shorter still. At eaves level runs a small parapet wall with projecting cope stone. A cast iron rainwater pipe drops down the centre of the façade to first-floor window sill level, then angles awkwardly to the right. The rubble field stone façade is detailed with brick dressings to all openings.

The rear of the building features two returns. The larger, gabled return is positioned to the right and rises three storeys. It has an opening to the centre of each level: a small opening to the roof space retains the remains of timber louvres; the second-floor opening is blocked with concrete blocks; the first-floor opening is semicircular arch-headed and fitted with a modern window frame; the ground-floor opening is obscured by heavy plant growth. The south-facing elevations of the ground and first floors are largely obscured by the second return. At second-floor level a small window with horizontal astragals is cut at the sill by an adjoining roof. The second return, to the left and slightly set back, is mainly two-storey. Its central portion is topped by a small 'sentry box' third-level extension perched on a corrugated iron lean-to roof. The sentry box features a segmental arch-headed window on its east face. To the left is a lower secondary section with a further lean-to roof rising alongside. The east face of this return is much obscured by plant growth, though a ground-floor window opening appears to exist.

Historical records show the site occupied on Michael Wills' town plan of Downpatrick from 1708 onwards. Although the building's appearance suggests a date around 1790–1800, the staircase features a thick moulded handrail characteristic of the mid-18th century. In the 1838 valuation returns the property was recorded as the home of William Smith, with a substantial rateable value of £26. The building most recently served as an office for the local Roman Catholic church before becoming vacant around 1995.

The house is listed within a conservation area.