The first church was rebuilt and enlarged in the 9th century, but it was badly damaged by the Normans invasions at the end of the same century. It was rebuilt by Bishop Milo through about 980 in the Romanesque style. Fragments of the sculptural decoration of this old church were found in 1864 and are displayed in the south collateral aisle of the present church.
In the 12th century, the Romanesque church was enlarged with the addition of a bell tower and a chapel dedicated to the Virgin Mary. The church was the site of the Council of Troyes that opened on 13 January 1129, hosted by Pope Honorius II. At the urging of Saint Bernard of Clairvaux, the Council granted official status to the Order of the Knights Templar, which became immensely influential throughout Christendom.
