The townland was once called Portcrusha, or Portcrushy, and it is under that older name that the crossing first appears in the historical record, bound up with centuries of assault, demolition, and reconstruction. The bridge visible today, roughly 120 metres long, is a multi-period structure whose two halves were not even built at the same time, and the ground beneath it has seen at least three entirely different crossings come and go since the early sixteenth century.

The earliest recorded bridge here was a wooden one, built in 1506 by Turlough O'Brien, son of Teige, son of Turlough, along with his brother Donnell, the Bishop of Killaloe, and the Bishop of Kilfenora. The Annals of the Four Masters note the construction; they also record its destruction just four years later in 1510, when an English force arrived, broke the bridge down, and camped overnight in the country. A subsequent crossing, apparently a mixed timber and stone structure defended by two castles built within the water itself, one on the Limerick side and one on the Clare side, was partially dismantled in August 1536 by an English force under the Lord Deputy. A contemporary account describes soldiers hacking through it with bills, swords, and daggers for lack of proper tools, and records that the Limerick castle was built of hewn marble with walls at least four metres thick, proof against artillery fire all day. The castles fell the following morning after the army filled a section of the river with bundles of wood and scaled the walls by ladder. By 1650, a Parliamentarian officer writing in his diary found no bridge at all, only the stump of a castle still standing in the water. The present stone structure began to take shape after the Siege of Limerick in 1691, when John Brown of Clonboy built the six Clare-side arches at his own expense for £800. The Limerick half was apparently not completed until roughly a century later, built by the County.

The bridge sits at the village of O'Briensbridge, which takes its name from this long history of crossings, and the contrast between the two halves noted by correspondents to the Limerick Chronicle in 1914 is still legible to an attentive eye. Researchers examining a 1833 elevation by Rhodes found the earlier configuration showed fourteen arches, with the Clare-side spans suggesting Tudor proportions comparable to a 1567 bridge at Athlone. The village is accessible via the R463 on the Clare side; the bridge itself carries the road, so it is crossed rather than visited as a monument. Looking downstream from the parapet, with the Shannon wide and slow beneath, it is worth knowing that somewhere in that water a castle once stood, and that men once tried to take it with ladders and bundles of sticks.