Two of its arches are now largely overgrown, the river having quietly retreated to the two central openings, while the structure itself appears to have been built in two distinct phases, the north-eastern end measuring 2.86 metres wide and the south-western end a noticeably broader 3.77 metres. Both sections rest on side walls that look to be of a single period, suggesting the widening came later, added onto an older core rather than built all at once.

The site has a longer history still. The Civil Survey of 1654 to 1655, a mid-seventeenth-century land survey compiled in the aftermath of the Cromwellian wars, records the 'ffoord of ffarnybridge', indicating that this crossing point was already named and recognised as a ford, a shallow stretch where the river could be crossed on foot or on horseback, long before anyone formalised it with cut stone. The two-phase construction of the bridge itself is considered significant because following the 1727 Road Act, Irish roads and their bridges were commonly upgraded and widened to accommodate heavier traffic. A bridge that was already widened before such improvements became routine may well have originated considerably earlier. The voussoirs, the wedge-shaped stones that form the curve of each arch, are described as well cut, and a single cut-water projects upstream on the north-eastern side to deflect the flow of water and protect the central pier. The span of each arch measures 2.4 metres wide and 2.4 metres high above what is now a stone and concrete river bed, and the flat-topped parapet runs to 0.8 metres in height across the width of the bridge.