St Mildred's is the oldest church within the city walls, dating from the 8th Century, evidence of which can still be seen in the west and south walls, including corner stone quoins. St Mildred was the great-great granddaughter of King Ethelbert.

To the pre-Conquest building, a 13th Century north chapel, a 15th Century north aisle, and a 16th Century south chapel were added. A 15th Century tower was demolished in 1832.

In 1486, St Mary de Castro, in Castle Street, was demolished, and merged with St Mildred's. (Its former churchyard is still a green space in Castle Street.) In 1626, Izaak Walton, author of 'The Compleat Angler', was married at St Mildred's.

Records at Cathedral Archives