The Salmon Weir Bridge was constructed in 1818 and it was intended to link the old Gaol (on the site of the cathedral) with the courthouse, a distance of no more than two hundred yards! It was also to provide a connection with the main road to Connemara. The river was first drained between 1845 and 1849 and a regulating Weir was built.

Between 1952 and 1959, the Corrib was again drained and the present regulating weir was built. This is the largest and most impressive weir in the country with a water flow of 4 million gallons per second at full flood, and 100,000 gallons per second at low flood. The tremendous rush of water through the weir is absolutely breathtaking at full flood, and the bridge is regularly lined with locals and tourists alike, absorbed by the spectacle.