Much of the western part of the church was demolished in 1811. Of the original ten bays of the nave only four remain, three of them up to the top. The twelfth-century south-west tower survives, now separated from the truncated body of the church. From the crossing are generated deeply-projecting transept arms; to the east comes the two-bay chevet terminated by a five-segment hemicycle surrounded by ambulatory. There is a single axial apsidal chapel with four free-standing slender columns at its mouth. The architecture of this chapel strikes one as being incredibly slender: what the visitor does not necessarily see is that the buttressing of the chapel, and of the chevet generally, is robust, raising the chevet aloft over its underpinnings in the crypt.
The church was originally built in the first part of the 6th century by Queen Clotilde, wife of Clovis on the site of a 5th-century church dedicated to Saint Maurice built by Saint Germain. Enlarged in the 9th century by Count Conrad with an avant-nef and a crypt (transfer of relics of Saint Germain in 859). Consecration in 865. Church was 100m long. The nave was rebuilt in the 11th century, and in the mid-12th century the south west tower (still existing) was built to match an older one to the north. Compare the towers of La Trinité in Vendôme, the south-west tower at Chartres Cathedral and the later tower of Vermonton.
The eastern end of the church was in a ruinous state by the second half of the thirteenth century and Abbot Jean de Joceval (1252-1278) decided to rebuild it. 1277 (demolition of old high altar) is thought to mark the start of the new work, interrupted by the death of the abbot. In order to establish the underpinnings of the eastern end of the church on the land sloping to the river Yonne, the old eastern rotunda of Sainte-Maxime was demolished and upper and lower chapels were built, dedicated to Saint Clement (lower) and Sainte-Maxime (upper). These chapels, in the form of decagons form the base of the axial chapel of the Virgin. The lower level of the ambulatory was begun at the same time; a break can be seen at the base of the triforium.
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