The 12th-century church had a round nave, with an aisle arcade, and a chancel with a semicircular apse. This chancel was replaced with a rectangular one, with a chapel added to its north side in Decorated style, in the late 13th or early 14th century. A second chapel was built later in the 14th century, on the south side, to which Perpendicular windows were added in the 15th century. These chapels have been identified respectively as St Katherine's Chapel, granted to the Bristol company of weavers by Edward I in 1299, and a chantry licensed to John Frauceys the younger by Edward III in 1331. Cloth weaving was the staple industry of Bristol in the late Middle Ages, and its centre was in Temple parish.