The exterior of the choir, with its four radiating chapels, its jutting cornices supported by modillions and columns with carved capitals, and its mosaic decoration of black and white stones, is the most interesting part of the exterior The rest of the church comprises a narthex surmounted by a tower, three naves and a transept, over which rises another tower.
Another interesting building is the Gothic chapel of Notre-Dame, with three naves, rebuilt by Louis XI., standing close to a medieval bridge over the Sienne.
It has two naves parallel, originally for the use of the nuns and the parishioners respectively.
Its general plan is that of a Greek cross, with two great naves and three aisles, twenty side-chapels and a magnificent high altar supported by marble columns and surrounded by a tumbago balustrade with sixty-two tumbago statues carrying elaborate candelabra made from a rich alloy of gold, silver and copper.
As an order of regular clergy, holding a middle position between monks and secular canons, almost resembling a community of parish priests living under rule, they adopted naves of great length to accommodate large congregations.