The River Irwell was an important highway for commerce in the early years of the city's development and initially it was navigable as far as a quay at the bottom of what is now Quay Street.  You can see in the engravings above and below, taken from the Casson map of the mid 1700s, and shown here with the permission of Chetham's Library, a collection of warehouses that were built at this trans-shipment point. 

Today a bridge carries New Quay Street over the River Irwell at this point and beside it stands what appears to be deserted warehouses.

Viewed from the Salford side you can see how the warehouse roof extends out over the river suggesting a kind of canopy used to facilitate the unloading of goods being hauled up into the warehouse or down into boats.

An RAF aerial photograph from 1953, shown here with the permission of English Heritage, shows the building (marked with a red dot) between the New Quay Street Bridge (a) and the warehouse complex that is the Marriott Hotel (b) today.  You will also note that along the Irwell there were other warehouses reaching out over the river.