Everywhere the builders were intent upon the problem of vaulting; but were influenced in the south by local conditions. In Provence, for example, the seat of Roman civilisation, not only does classical influence appear in the details, but the vaulting is of the old Roman kind. =Notre Dame=, =Avignon=, is a well-known instance. And the barrel-vaulting was continued throughout the neighbouring Duchy of Aquitaine. Here, however, another influence intervened. The district had close commercial relations with Venice, Ravenna, and Byzantium, and it is reflected in the domical vaulting of many of the churches. =S. Front=, =Perigeux=, for example, resembles S. Mark’s, Venice, in having the plan of a Greek cross, surmounted by five pendentives. The arches, however, are _pointed_; of great depth, resting on piers, pierced with passages. In the =cathedral= of the neighbouring city, =Angoulême=, a Latin cross is substituted for the Greek in plan. The aisleless nave is surmounted by three stone domes, roofed on the exterior. Over the crossing rises another dome, visible outside, which is raised upon a drum that is pierced with pointed windows, disposed in pairs. The southern transept is still crowned with a tower, its fellow to the north having been destroyed in 1568. This building served as a model for the =Abbey of Fontevrault= in =Anjou=. In Burgundy the most renowned of the numerous monastic establishments was the =Benedictine Abbey= of =Cluny=. Until the building of the present S. Peter’s, its abbey church was the largest and most magnificent in Christendom. The plan was a basilica with double aisles, the east end terminating in a _chevêt_ (shě-vay´); that is to say, an apse surrounded by a circular aisle, divided into chapels; in this case five in number. The nave was arcaded with pointed arches and spanned by an immense barrel vault. Groined vaulting, on the other hand, is supposed to have covered the aisles. Groined vaulting takes the place of barrel-vaulting in the nave of the =Church of Vézelay=, and was also used in the ante-chapel, erected some thirty years later. But by this time the builders, in order to reduce the thrust, adopted a pointed section for the ribs--the first instance in France of the pointed groined vault, which was successfully developed later by the Gothic architects. It is to be noted that the early vaulting, erected by the Clunisian architects, compelled the abandonment of the clerestory windows. The thrust of the great barrel vault of the nave was sustained either by high side aisles with either transverse or groined vaults over the bays, or by barrel vaults over the aisles, which in turn were supported by the massive outer walls. For the use of the flying buttress had not yet been adopted.