See Caistor St Edmund for the Roman settlement in Norfolk.

Caistor is a town in Lincolnshire, England and was, as its name implies, originally a Roman fortress. Only a few fragments of the fourth century Roman walls remain, but the church of Saints Peter and Paul has an Anglo-Saxon tower. The picturesque Market Square is surrounded by handsome houses, many of them Georgian. Caistor has a population of around 2,500 people. It lies on the edge of the Lincolnshire Wolds and on the Viking Way long-distance footpath.

Sir Henry Newbolt, author of "Drake's Drum", was educated at Caistor's old Grammar School. Notable buildings in the town include Caistor Grammar School, founded in 1633, and Sessions House, built in 1662.