Glenavy Bridges, Crumlin Road, Glenavy, Lisburn, Co Antrim

Glenavy Bridges comprises two separate but closely related masonry structures crossing watercourses at the north end of Glenavy Village, near the junction with the Belfast Road.

The principal bridge is a triple-arch masonry structure carrying the Crumlin Road over the Glenavy River. Built from random rubble basalt, it is probably of mid-18th century date and exemplifies the vernacular style of bridge construction of that period, using local materials with minimal ornament. The three arches are of equal size with segmental profiles, typical of bridges from this era. Angled cutwaters on both upstream and downstream elevations rise to just below the parapet tops. The parapets are coped with squared random rubble, and the carriageway is slightly curved, accommodating two lanes of traffic and a footpath.

The bridge's abutments and piers have been underpinned with concrete, a structural necessity that somewhat diminishes its aesthetic character. The most significant historical feature is evidence of widening, probably in the later 18th century. This is visible in subtle differences between the upstream and downstream faces: the upstream voussoirs are of roughly-dressed quarried basalt rubble whereas the downstream ones are of narrower split basalt rubble. The arch ring and spandrels are set back from the parapets and abutments on the upstream side, while only the arch ring is recessed downstream. A clear break along the middle of all three arch soffits indicates that the upstream half was added to the existing downstream half, effectively doubling the bridge's width. The 1833 Ordnance Survey Memoir records the bridge as measuring 24 feet wide and 80 feet long, confirming this width was achieved before that date, likely during the later 1700s as traffic increased along this important route between Antrim and Lisburn. The bridge walling extends for considerable distance along the Crumlin Road, particularly on the east side, consisting of low rubble stone walls with roughly squared stone copings.

The downstream elevation carries a pipe on cantilevered steel brackets just above arch crown level. The river bed beneath the arches has been concreted to prevent erosion, with pitched rubble immediately downstream. The south end of the upstream parapet has been damaged by vehicle impact and is now missing. A vehicle impact and is missing.

Just east of Glenavy Bridge is a small arched rubble masonry bridge of similar age and construction, carrying the Belfast Road over a stream that discharges into the Glenavy River just above the main bridge. Although physically separate, the two structures are regarded as a single architectural entity. The smaller bridge has a segmental arch with roughly dressed quoins. Its left-bank approach wall sweeps around towards the approach wall to Glenavy Bridge, with a modern tubular steel gate mounted on concrete posts filling the gap between the two walling sections. The upstream face of the smaller bridge is now obscured by a later culvert running diagonally from a rubble masonry weir that formerly directed part of the stream to Glenavy Mill. The culvert has a semicircular brick arch of two courses of machined brick over random rubble abutments, a 20th century addition. All water now flows through the culvert, as the take-off to the mill's headrace has been infilled.

Circumstantial evidence dates Glenavy Bridge to the mid-18th century. The road to Crumlin is shown crossing the river at this point on Taylor & Skinner's 1777 map of Ireland, and a crossing appears on Lendrick's 1780 map of County Antrim. The bridge is cited as 'Glenavy Br' on the 1832–33 Ordnance Survey six-inch map. The 1833 Ordnance Survey Memoir for Camlin Parish describes it as "consisting of three semicircular arches" and notes that these are "plain old structures, suitable in every respect but not worthy of further notice". It is uncertain whether the single-arch bridge is contemporary with Glenavy Bridge, though it appears on the same 1832–33 map. The bridge is of local historical interest as a well-preserved and still-functioning 18th century structure, and is of industrial archaeological interest.