18 Arthur Street, Hillsborough, County Down, BT26 6AP

18 Arthur Street is a single-storey stone terraced house with attic dormer, built circa 1850 as part of a row of workers' housing erected for the Downshire Estate during the mid nineteenth century. It is located off Ballynahinch Street, north of St Malachi's Parish Church in Hillsborough.

The building displays a rectangular plan form with a pitched natural slate roof and two dormer windows. Clay ridge tiles and replacement uPVC rainwater goods sit above coursed rubble masonry walling with painted red brick and sandstone surrounds to doors and windows. A replacement brick chimneystack, shared with the adjoining building, carries two clay pots. A sandstone elliptical arched alleyway with long-and-short surrounds provides access, with a matching half-circle sandstone label moulding painted black.

The front elevation faces west and is asymmetrically arranged, with the ground floor window positioned to the right of the front door. The arched alleyway, located to the left of the front door and shared with the adjoining dwelling, formerly provided access to the rear yard and now serves as secondary access to a modern single-storey extension. Windows are modern top-hung timber casements, painted white, with large sandstone cills and single-brick flat arches over, topped by robust half-circle sandstone label mouldings painted black. The front door is replacement timber sheeted, painted pale blue. The left elevation forms part of the passageway between number 16; the right elevation abuts number 22.

The building retains its original modest façade with dressed stone archway and stone hood mouldings, although it has lost its original doors and windows and had many original materials replaced internally during recent renovations. A modern single-storey extension abuts the rear elevation. Dormers were replaced in 1990 and skylights installed in 1999.

Arthur Street was constructed in stages throughout the first half of the nineteenth century. The earliest houses, appearing on the 1833 Ordnance Survey map and dating from the 1820s, were erected to accommodate workers and tenants of the Downshire Estate. The town plan of circa 1834 identifies six dwellings on the street. By the second edition Ordnance Survey map of 1858, the remainder of the street as it appears today is shown. The earliest phase used random rubble masonry with granite mouldings and arched alleyways. A second phase of four dwellings, using sandstone in place of granite with squared galletted rubble walling, followed. The later part of the street, including number 18, was constructed circa 1850 using more regularly cut stone laid to courses.

This building, as part of the later half of the street, was identified in Griffith's Valuation of 1862 under the ownership of John Smith, valued at £2 15 shillings. The valuer noted that rents were "moderate". The house was valued slightly higher than its neighbouring properties, as it claimed ownership of the passageway and enjoyed an additional bedroom located above it. Occupiers changed hands various times thereafter. All houses on Arthur Street originally came with a rear yard containing a pit for household waste and a dry toilet. Coal was typically stored in a hole under the stairs adjacent to the living room, and water was supplied from either a tap at the top of Arthur Street or a pump at the end of Wapping Street.

Number 18 was listed in 1974. Despite twentieth-century alterations and additions, it constitutes an important part of the overall character of Arthur Street, forming part of a pair of matching terraces lining the street. The street is accessed by a single entrance from Ballynahinch Street, with the other end closed by a large rubble masonry wall, which formerly contained an arched opening now infilled.