12th Century
The current site of the church itself was built by Robert, 1st Earl of Gloucester in 1121 and consecrated in 1137. The original structure of the church was a cruciform without aisles, but with the increases in population, the north and south aisles were added within 40 years of each other around the start of the 13th century.
Read more about this topic: St Mary's Church, Luton, History