21 Altmore Street, Glenarm, Co Antrim, BT44 0AR

21 Altmore Street is a relatively plain, low-proportioned two-storey terraced house of possible pre-1832 construction, situated on the west side of Altmore Street in Glenarm, County Antrim. A substantial level of original internal period detail survives. The house is privately owned and falls within a conservation area.

The front (east) elevation is asymmetrical. Slightly right of centre on the ground floor is a rather low door opening fitted with a panelled timber door, plain fanlight, and moulded cement surround — a surround that matches the architraves found inside the house. To the right of the door is a plain sash window with a matching moulded surround. To the left, but set slightly further across, is a similar window. At first-floor level are three similar windows sitting directly above the corresponding ground-floor openings. The façade is finished in painted lined render with plain quoins; the quoins to the right are notably wider than those to the left.

To the rear, the ground floor has a full-width flat-roofed return, extended to its present size some time in the early to mid 20th century. On the ground floor of this rear elevation, to the left, is a large recent timber window; to its right is a recent glazed door; further right again is a smaller recent timber window; and at the far right is a half-glazed door. At first-floor level are three recent timber windows with top-hung openings. The central window is lower, lighting the half landing, while that to the left is considerably shorter. The rear walls are finished in unpainted roughcast render. The gabled roof is slated and has three small skylights to the rear. There are two shared rendered chimney stacks. The rainwater goods appear to be mainly cast iron.

Altmore Street takes its name from the Altmore River, a narrow brook flowing from the high ground to the south-east down to the Glenarm River to the west. The earliest documentary reference to building plots in its vicinity occurs in a lease of August 1673 mentioning 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 presence of a "street" at that date. Many of the earliest houses may have been built on the western side of the street, since prior to the walling in of the estate grounds near Glenarm Castle in the 1750s the village fronted onto both sides of the Glenarm River. Some buildings on this side of the street may originally have faced the river: the present no. 15, for instance, appears to have originally had an almost symmetrical "rear" elevation facing the river and a markedly asymmetrical "front" elevation, while no. 29 has a 1739 date stone on its river-facing side rather than its street-facing front.

The earliest surviving map of Glenarm, drawn up by John O'Hara in 1779, shows the street fully developed on both sides, with the western terrace stretching 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 led to radical changes to the street layout: much of the terrace on the eastern side was pushed further eastward, allowing for a broader and slightly grander approach to the estate. No published account of the development of Glenarm appears to mention this widening, but the discrepancy between the alignment of the eastern terrace on the 1832 Ordnance Survey map and that of 1857 strongly suggests it occurred. This theory is further supported 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 by the fact that many of the buildings recorded in the 1833 valuation of the eastern side of the street seem to bear no relation to those in the 1859 valuation — as though all had been demolished and rebuilt. The age and condition grading used in the 1859 valuation indicates that most of the rebuilt dwellings were around twenty years old or slightly more at that date, placing much of the redevelopment in the mid to later 1830s. This corresponds 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 untouched by these mid-19th-century changes, with some of the buildings visible today possibly pre-dating the 1830s; however, some properties at the very southern end were cleared away with the construction of the Town Gate and the land incorporated within the estate.

This particular site is shown as occupied by a building on both John O'Hara's 1779 map and the 1832 Ordnance Survey map. On the 1779 map the plot is recorded as a "tenement unset," meaning vacant at that time. The present house is likely to be the building of the same dimensions recorded in the 1859 valuation notebook, at which point the property was leased from Lord Antrim by a William Thompson. It was described as having three rooms below, four above, a small garret, and a small single-storey rear return (subsequently extended in the 20th century). The valuers graded the house "B," indicating, by their own reckoning, a building at least twenty years old. The moulded surrounds to the front openings and some of the interior decoration suggest that a craftsman of considerable skill worked on this house at some point — possibly a craftsman engaged on Glenarm Castle itself, perhaps during the major alterations to the castle that took place in the 1820s.