Killyvally Bridge, Bridge Street, Garvagh, Coleraine, Co Londonderry, BT51

Killyvally Bridge is a four-arch masonry road bridge spanning the Agivey River at the east end of Garvagh, built in two distinct phases that reflect contrasting construction methods and periods.

The original bridge was constructed in the early 19th century on the downstream (north) side. This section is built throughout in random rubble basalt, with stones that are generally rounded, suggesting they were collected from the earth rather than quarried. The piers feature angled cutwaters that rise to arch spring level and taper towards the top. The four segmental arches are fitted with split stone voussoirs. The two central arches are slightly wider and higher than those at the ends. The parapet has dressed stone copings with a small drain hole at the centre, and a metal plaque bearing the bridge's name is fixed to the east end. Plastic planters line the top of the parapet.

Later in the 19th century, the bridge was widened by extending it upstream. The upstream section shows a markedly different architectural treatment, with squared basalt rubble forming the abutments, piers and arch soffits, while the spandrels and parapets are of undressed rubble. This squared stonework, more sharply angular than the downstream side, indicates stone from a quarry. The piers on this face have curved cutwaters capped with sandstone, rising to arch spring level. The arches match the downstream arches in size and profile but have rock-faced voussoirs and squared rubble soffits. The parapet carries dressed sandstone copings, a metal name plate at the west end, and planters. A small metal commemorative plaque commemorating someone possibly drowned nearby is attached to the upstream spandrel above the middle pier. A clear break in construction is visible along the abutments, piers and arch soffits between the two phases.

The slightly curved deck accommodates two traffic lanes and a footpath along each parapet. An unsurfaced ramp bounded by a random rubble basalt wall provides access to the upstream left bank. A low weir stands just downstream, built to prevent the river bed from eroding downward in the bridge vicinity.

Historical records show a road crossing the river at this location on Taylor & Skinner's 1777 map. The 1832 Ordnance Survey map clearly depicts a bridge, and the 1836 Ordnance Survey Memoir notes that an 18th-century bridge was swept away by flood around 1802 and subsequently rebuilt. The memoir describes it as 15 feet across with five arches, one of which served as a tailrace for a corn mill just upstream on the right bank. The name Killyvally Bridge is explicitly noted from the 1848-53 Ordnance Survey map onwards. By comparing the 1905 map with the 1853 edition, the upstream widening can be dated to the intervening period, bringing the bridge to its present width of approximately 30 feet.

The bridge forms part of the main road into Garvagh from the east and is situated at a location of local historical significance. A graveyard stands at the upstream west end. On the downstream side at this end are a car park, public toilets and a drain outfall. Gardens occupy both sides of the east end.