The apse vault used in Sens Cathedral unites a part of the sexpartite vault system leading up to it and was designed to create uniform pier intervals of both straight and curved areas of the grand arcades. Such a vault system can only be constructed at the same time as the positioning of the grand arcade piers. This constraint proves that the rib-vaulting for Sens cathedral had been intended from the starting point of its construction, i.e., around 1140.
By introducing round-pier structures into the central nave, Sens Cathedral produced not only a regular alternation of round and compound piers but also a united series of sexpartite vaults and an apse vault with uniformed pier intervals.
