VILLAGE HISTORY
How Did O' Brien's Bridge Get Its Name?

O' Brien's Bridge is situated on the Lower Shannon River, and takes its name after the bridge crossing the river at this point.
The first bridge was built in 1506 by Turlough O'Brien, First Earl of Thomond, who possessed a manor at the end of the bridge at the Clare side, and by his brother, the Bishop of Killaloe. They were descendants of Brian Boru, who was killed at the battle of Clontarf in 1014. 

The first bridge was a wooden structure.  During the war between the provincial kings, each trying to become high king, Gearoid Mor, the great Earl of Kildare, burnt down the bridge in 1510.   
The O'Briens now realized the weakness of undefended wooden bridges and replaced the structure with a "Great Bridge".   
Castles of Marble were built on each side of the bridge with walls 12 ft. thick and well defended.  Each was built in the water a short distance from the land and was connected by a massive wooden bridge of seven arches and a height of 15 ft. above the water.

In 1537 Conor O'Brien and his brother Murrogh, sons of Thurlough, who owned land at both the Clare and Limerick side of O'Brien's Bridge sided with Silken Thomas in his rebellion against Henry VIII and the Lord Deputy, Leonard Gray, who made an attack on the bridge.  The battle lasted for several days ending with the destruction of the "Great Bridge".  A stone bridge with twelve arches then replaced the bridge.

The bridge, having been built by the O' Briens, became known as O'Brien's Bridge, and gradually the village and eventually the town land assumed the name.

The old name for the place was Ath Caille Gallaigh, "The Rough Ford of the Wood", which was one of the three principal fords of Ireland together with Ath Cliath (Dublin) and Ath Luain (Athlone)