18 Castle Street, Newry, Co Down, BT34 2BY

18 Castle Street, Newry, is an early Georgian classical town house, part of a terrace of three, dating from 1760–1779. It stands on the east side of Castle Street at the left end of the group and is Grade B+ listed.

The building is three storeys high with basement and attic spaces. It is two bays wide with a gabled artificial slate roof featuring a granite knee-stone and coped verge on the left side, with stone copings to the party wall on the right. A rendered chimney rises from the left gable. Half-round metal rainwater goods with downpipe serve the right elevation.

The street façade is constructed of rubble granite brought to courses, with a projecting eaves course. At ground floor, the right bay contains a pair of modern metal gates within a segmental-headed coach arch trimmed with ashlar granite, flanked by granite carriage bollards at the base of each jamb. The left portion retains a modern but traditional painted timber shop front comprising a central pair of framed and sheeted outer doors with decorative transom, flanked by timber pilasters on each side with pairs of fixed timber windows. Four timber pilasters support a projecting timber fascia inscribed 'Stephen Fitzpatrick and Co.' with '18' marked over the end pilasters. The first floor contains four regularly spaced 6/6 sliding sash windows with exposed boxes and granite cills. The second floor has four 6/3 sliding sash windows, diminished in height, with three lighting the first bay and one the second. The left gable is cement-rendered with a large fascia at second floor displaying occupant signage and two modern up-lighters below. The right gable forms the party wall with the adjacent property.

The rear elevation shows rubble granite walls painted up to the meeting rail of first floor windows. The left bay has a modern timber half-door within a coach arch at ground floor, with a 6/6 sliding sash window above at first floor and a diminished 6/3 sash at second floor, neither with cills.

Three gabled returns project from the right side. The first return is three storeys high with an artificial slate roof. Its left cheek has a modern five-panel painted door with three-pane transom at ground floor, sharing a timber frame with an adjacent 6/6 sliding sash window, both set within a segmental brick-headed arch infilled with random rubble. Two further 6/6 sashes occupy the ground floor right, with two three-paned fixed windows lighting the basement immediately above ground level. First floor contains three 6/6 sliding sashes and second floor three diminished 6/3 sashes, all in line with ground floor openings. All windows to this elevation have shallow segmental brick heads but no cills. The right cheek is dashed. A 6/3 sash window lights a half-landing between first and second floors, and a three-paned window on the upper half-landing to the attic has the left two panes in a sliding timber frame. An exposed section of the first return's gable wall contains a three-paned quarter-oriel at ground floor with rendered and painted walls, modern fixed windows with top-hung transoms, and support on a metal I-beam. A t+g basement door below is accessed by steps.

The second return is slightly lower and three storeys high with artificial slate roof and random granite rubble walls. Its left cheek has a 1/1 modern fixed timber window at ground floor, and 1/1 sashes on each floor above (the top one diminished), all with segmental brick heads but no cills. Both the gable and right cheek are dashed without openings. The yard is enclosed at the rear by a modern timber and sheet metal outbuilding.

The building appears on John Rocque's 1760 map of Newry. It is shown definitively on the 1838 valuation map, where it was valued as a house and store at £30. It appears on the 1861 Ordnance Survey map with its returns. An 1863 valuation described it as three and one-third storeys high, noting it as a "large concern with a large yard but seems to be doing little or no business."

The building retains most original features and is well-proportioned and elegant, though it has experienced alterations to ground floor elements. It is situated within a conservation area and is now in office use.