What is "caistor"

Caistor is a town and civil parish situated in the West Lindsey district of Lincolnshire, England. As its name implies, it was originally a Roman castrum or fortress. It lies at the north-west edge of the Lincolnshire Wolds, on the Viking Way, and just off the A46 between Lincoln and Grimsby, at the A46, A1084, A1173 and B1225 junction. It has a population of 2,601. Its name comes from the Anglo-Saxon ceaster (" Roman camp" or "town") and was given in the Domesday Book as Castre.