One of the two bridges by which someone could enter Galehaut’s land of Sorelois. The other was the North Wales Bridge (North Wales Causeway). It was, such as the other bridge, guarded by a knight, ten armed sergeants and a barred tower. Any knight defeated while trying to cross either bridge had to stay and help guard it.
It is unclear why the bridge was called the "Irish Bridge" - it certainly could not have connected Sorelois to Ireland, although it was said to be exceedingly long. Parts of it went underwater. The description of it is reminiscent of the Underwater Bridge of Chrétien’s Lancelot.