The original nave was altered during the first half of the 16th century. Stained glass windows, paid for by the abbot and parishioners, were ordered from Maîtres Eugène Hucher and his son (in business from 1853 to 1906) under the supervision of the Carmel of Le Mans.
Walking up the central nave towards the choir:
During the restoration of this part of the church in 2017, under the sole charge of BPN, frescoes were uncovered.
They represent the four evangelists: St Matthew, St John, St Luke and St Mark.