The winding Avon from the mouth at the River Severn down to the Port of the City of Bristol has always been both the blessing and the curse for Bristol. Blessing because it was easier to defend and sheltered; curse because of the massive tidal range and the sharp bends. It was why Bristol City Docks moved from important international port to City Centre leisure and housing as commercial shipping got too large for the river. See Seven Ages of Bristol Docks.
On the banks of the River Avon stands the Old Powder House. It was built in 1775-6 to store gunpowder, which was not allowed into Bristol docks lest it ignite by accident in the crowded Bristol docks, thereby setting fire to every ship in the city! It is a grade II listed building.