The Community Assembly of Colchester is located in a city in Essex and it is the second-largest settlement in the county. Colchester occupies the site of Camulodunum, the first major city in Roman Britain and its first capital. Colchester, therefore, claims to be Britain's first city. 

There are several theories about the origin of the name Colchester. Some contend that is derived from the Latin words colonia (referring to a type of Roman settlement with rights equivalent to those of Roman citizens, one of which was believed to have been founded in the vicinity of Colchester) and castra, meaning fortifications (referring to the city walls, the oldest in Britain). The earliest forms of the name Colchester are Colenceaster and Colneceastre from the 10th century, with the modern spelling of Colchester being found in the 15th century.

There is evidence of a hasty re-organisation of Colchester's defences around 268–82 AD, followed later, during the fourth century, by the blocking of the Balkerne Gate. John Morris suggested that the name Camelot of Arthurian legend was probably a reference to Camulodunum, the capital of Britannia in Roman times.