 What remains of the foundations of an early rectangular building near the southern part of the current cathedral might also be contemporary with Justus or may be part of a Roman building.Together with Mellitus, the Bishop of London, Justus signed a letter written by Archbishop Laurence of Canterbury to the Irish bishops urging the native church to adopt the Roman method of calculating the date of Easter.This letter also mentioned the fact that Irish missionaries, such as Dagan, had refused to share meals with the missionaries.