Roman times

The existence of a British settlement at Gloucester (Caer Glow, Gleawecastre, Gleucestre) is not confirmed by any direct evidence, but Gloucester was the Roman municipality of Colonia Nervia Glevensium, or Glevum, founded in the reign of Nerva. Parts of the walls can be traced, and many remains and coins have been found, though inscriptions are scarce. Evidence for some civic life after the end of Roman Britain includes the mention in the Historia Brittonum that Vortigern‘s grandfather ruled Gloucester. According to the Anglo-Saxon Chronicle, Gloucester passed briefly to Wessex from the Battle of Deorham in 577 until 584, when it came under the control of Mercia.

Saxon times

Gloucester (Glowancestre, 1282) derives from the Anglo-Saxon for fort (Old English ceaster) preceded by the Roman stem Glev- (pronounced glaiw). In Old Welsh, the city was known as Caerloyw, caer = castle, and loyw from gloyw = glowing/bright. Gloucester was captured by the Saxons in 577. Its situation on a navigable river, and the foundation in 681 of the abbey of St Peter by Æthelred, favoured the growth of the town; and before the Norman Conquest of England, Gloucester was a borough governed by a portreeve, with a castle which was frequently a royal residence, and a mint.

In the early tenth century the remains of Saint Oswald were brought to a small church in Gloucester, bringing many pilgrims to the town.

The core street layout dates back to the reign of Ethelfleda in late Saxon times.