Apart from Fulbert’s crypt the earliest part of the Chartres Cathedral is the west end. Architecturally, its most prominent features are the two towers. These were conceived separately and imply two phases spread over a long period of time.

A new tower, at the north-west, is mentioned around 1140. For it to be built at all Fulbert’s tower porch had to be removed; this is usually explained by a fire in 1134, even though the cathedral was said to have been spared.

This new tower was originally free-standing and gave access via a long passage to the crypt, where a new statue of the Virgin had recently been displayed.

The east end was altered at the same time, perhaps on the model of Saint-Denis Abbey.

These works must also have included a new façade for Fulbert’s nave, but its form is not known. A few years later the south-west tower was built and the west front moved forward to its present position.

The south-west tower was stylistically a major advance on its companion, which had been designed in the Romanesque manner for a wooden superstructure. This was replaced in the 16th century by Jehan de Beauce’s elegant Flamboyant spire. The extension of the nave brought the pan of the cathedral (apart from the transepts) up to its present limits.