20 Altmore Street, Glenarm, Ballymena, Co Antrim, BT44 0AR

No. 20 Altmore Street is a plain, rendered two-storey terraced house dating from approximately 1835 to 1840, situated in the middle of the terrace on the east side of Altmore Street in Glenarm, County Antrim.

The symmetrical front façade faces west. At the centre of the ground floor is a panelled timber door with a rectangular five-pane fanlight above it. To the left of the doorway is a sash window with Georgian panes in a 6/6 configuration, and a similar window sits to the right. Three further sash windows of the same type light the first floor. The entire front façade is finished in painted render.

To the rear, roughly in the centre of the ground floor, is a mostly glazed door. To the left of this is a single-storey, flat-roofed kitchen extension dating from around 1980, with a glazed door and large modern window. To the far right of the rear ground floor is a plain sash window, with three more sash windows above on the first floor. The rear façade is finished in unpainted roughcast render. The gabled roof is slated and has two small cast iron skylights to the rear. There are two rendered chimneystacks, both shared with neighbouring properties. Rainwater goods appear to be a mixture of cast iron and PVC. To the rear there is also a large split-level outbuilding that has been somewhat modernised in recent years.

Altmore Street takes its name from the Altmore River, a narrow brook flowing from high ground to the south-east down to the Glenarm River to the west. Documentary records relating to building plots in the vicinity date back to a lease of August 1673, which mentions a "housestead, garden of tenement extending back to Altmore Brook," with further leases of December 1678 referring to "tenements" on the "south side of Altmore" and confirming the existence of a "street" at that date. Many of the earliest houses in the street may have been built on the western side, since prior to the walling in of the grounds immediately surrounding Glenarm Castle in the 1750s, the village fronted onto both sides of the Glenarm River. Some buildings on the western side may originally have faced the river rather than the street: the present No. 15 appears to have originally had a near-symmetrical rear elevation facing the river and a markedly asymmetrical front elevation facing the street, while No. 29 has a 1739 datestone on its river-facing side rather than on its street-facing front.

The earliest surviving map of Glenarm, drawn by John O'Hara in 1779, shows the street fully developed on both sides, with the terrace to the west extending further south than it does today, beyond the line of the present Town Gate to the Glenarm Castle estate. The construction of the Town Gate sometime between 1832 and 1857 appears to have brought about radical changes to the street's layout: much of the terrace on the eastern side was pushed further eastward, creating a broader and slightly grander approach to the estate. No direct documentary record of this widening has been found, but it is suggested by the discrepancy between the alignment of the eastern terrace as shown on the Ordnance Survey maps of 1832 and 1857, by an 1830 illustration of the town (by T. M. Baynes, published in Ireland Illustrated, London 1831) which shows the two sections of the eastern terrace out of alignment and suggests most of those houses were still single-storey at that date, and by the apparent lack of correspondence between properties recorded in the 1833 valuation of the eastern side of the street and those recorded in the 1859 valuation, as though all had been demolished and rebuilt in the intervening period. The age and condition gradings used in the 1859 valuation indicate that most of the rebuilt dwellings were approximately twenty years old or slightly more at that time, placing the main phase of redevelopment in the mid to late 1830s. This is consistent with a remark in the Ordnance Survey Memoirs of 1835 that "some two storey houses of a tolerable description have been recently built in Glenarm, intended for the accommodation of lodgers during the bathing season." The western side of Altmore Street may have remained largely unaffected by these mid-19th century changes, with some buildings possibly predating the 1830s, though some properties at the very southern end were cleared for the construction of the Town Gate and the land incorporated into the estate.

No. 20 appears to date from the mid to late 1830s, consistent with the general redevelopment of the eastern side of the street following its widening. It is almost certainly the property recorded in the 1859 valuation as being probably just over twenty years old and graded "B+." At that time the occupant was Francis Saunderson, who leased the property from a William McCloy. The kitchen extension to the rear is a relatively recent addition and does not appear on the 1:2500 Ordnance Survey map of 1973.