It was planned simply with a nave roofed by four cupolas and a choir with four radiating apsidal chapels. Later on in the century the love of building places of worship larger and more suited to the growing desire for an enriched ceremonial and elaborate ritual resulted in the addition of transepts surmounted by towers, which gave to the Cathedral of Saint Pierre at Angoulême the distinction of being one of the first, if not the first, of domed churches built on the plan of a Latin cross. Of the two towers only one, the northern tower, exists to this day, the southern transept being roofed by a flat conical dome. Certain further additions were made about the same time, such as the western façade with its sculptured portal. The black lines of the ashlar work, as if ruled with a lead pencil, detract very much from the impressiveness of the interior, as they give undue emphasis to the horizontal joints and arrest the eye in its first natural flight from floor to vault.
Saint Pierre at Poitiers is a church of a very different description. Certain characteristics it has which connect it with the Angevin style, but unlike most of the Angevin churches, it has aisles throughout. From the outside the appearance is that of a single mass, long and low, and very wide, for the aisles are nearly as broad as the nave; as at Bourges, there is no central tower at the crossing; but then at Bourges we have a great French church, a mighty mass rising sheer up from the ground, unbroken by any transept; here at Poitiers there are transepts, but the line of their towers comes below the line of the roof, and the effect given is one of length without height. Height is also wanting in the two unfinished and unequal west towers, and the east end literally falls flat, by reason of its bare terminal wall; the apse, to which one grows so accustomed in a French church, is seen only from the interior. It is oblong in plan, showing, as M. Viollet-le-Duc points out, no sign either of choir or sanctuary. The transepts are more like side chapels with altars on their eastern walls. There is no sign of northern influence, and the church is in many of its features unique and without imitators. Certain details of construction bring it into line with St. Maurice at Angers; it is an ordinary example of the churches of Poitou, with their three naves of equal height and Byzantine cupolas.