Both the north and south facades have rose windows of 11 m in diameter.

The Gothic cathedral of St Pierre replaced an older structure, which had been damaged by fire in the 1180s and again in 1225. This former cathedral is thought to have been begun in the late 10th century; the three western bays of its nave, known since the Middle Ages as Notre-Dame de la Basse-Oeuvre, still stand (although much restored). The Gothic choir was constructed between 1225 and 1272, but in 1284, 12 years after its inauguration, a large part of the superstructure collapsed. The transept was finished under the direction of the greatest master mason of French Late Gothic, Martin Chambiges. In the 1560s an over-ambitious lantern tower, rising some 130 m above the pavement, was erected over the crossing, but it collapsed on Ascension Day, 1573.