Because the valley sides slope unevenly, the piers do not stand at equal heights; they diminish as the structure climbs the valley flank, giving the whole thing an almost staggered appearance, as though the bridge is carefully negotiating its way up the hillside rather than simply spanning it. The voussoirs, the wedge-shaped stones that line each arch and hold it in compression, are cut to stand proud of the surrounding masonry, giving each opening a bold, deliberate framing.

The viaduct was built in 1849 for the Great Southern and Western Railway, one of the major arterial lines of nineteenth-century Ireland. Its contractor was William Dargan, the County Carlow-born engineer and entrepreneur who built much of the early Irish railway network and who, by the time this structure went up, was arguably the most significant figure in Irish railway construction. That a man of his scale was involved in a relatively modest crossing over the Blarney river speaks to how thoroughly the GSW R project was rolled out across Cork, threading rail connections through awkward topography wherever the route demanded it. The combination of cut stone and careful engineering here was not decorative ambition so much as a practical response to a difficult site.