The bridge crossing the River Barrow at Athy has a name that tends to catch people off guard. "Crom a boo" is a war cry associated with the Fitzgerald dynasty, the Earls of Kildare, and its attachment to this particular crossing speaks to how contested and consequential this stretch of water once was. The Barrow here runs broadly southward, and for centuries the ability to cross it at this point meant control over movement between two halves of a town and, in a wider sense, over a significant corridor through the Irish midlands.

The crossing almost certainly has Anglo-Norman origins, with a bridge probably first built during the thirteenth century to connect the settlements that had grown up on either bank. Documentary evidence, however, is slow to appear; the first direct reference to a bridge here does not come until 1423. Whatever stood then was not built to last without effort. The structure was damaged and repaired on several occasions during the late medieval period, and again in 1650, during the Confederate Wars, the conflict that convulsed Ireland in the mid-seventeenth century as various factions, including Catholic Confederate, Royalist, and Parliamentarian forces, fought for control of the country. Throughout this period the bridge sat in the shadow of White Castle, a fortification on the eastern bank of the Barrow whose purpose was precisely to defend this crossing point. The present bridge, the one visible today, dates from 1794, a relatively late construction that replaced whatever had accumulated, and been patched together, over the preceding centuries.