Keynsham is a town and civil parish between Bristol and Bath in Somerset, south-west England. It has a population of 15,641. It was listed in the Domesday Book as Cainesham, which is believed to mean the home of Saint Keyne.
The site of the town has been occupied since prehistoric times and is scattered with Roman remains. It became a medieval market town, after Keynsham Abbey was founded around 1170. It is situated at the junction of confluence of the River Chew and River Avon and was subject to serious flooding before the creation of Chew Valley Lake and river level controls at Keynsham Lock in 1727. The Great Flood of 1968 inundated large parts of the town. It was home to the Cadbury's chocolate factory, Somerdale, which opened in 1935 as a major employer in the town.
It is home to Memorial Park, which is used for the annual town festival and several nature reserves. The town is served by Keynsham railway station on the London-Bristol and Bristol-Southampton trunk routes and is close to the A4 road which bypassed the town in 1964. There are schools, religious, sporting, and cultural clubs and venues.